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The taxonomy of the family Linaceae has not been updated for over two decades and, particularly in Mexico, there is no work evaluating the taxonomic status of all its species. This study provides an update and integrates each of the taxa in the family Linaceae distributed in Mexico. Specimens of plants of this family collected from across the distribution range in Mexico and deposited in herbaria and digital databases, as well as specialized literature, were reviewed. Twenty-four native and one introduced species belonging to two genera, in addition to two varieties, were recognized for the family; the rate of endemism is more than 50% and all native species are under some threat. Reflecting the previously limited knowledge of the group, many of the specimens that we studied had been misidentified. We provide morphological descriptions, supplemented with photographs, illustrations, morphological descriptions, synonymy, ecological data, assessment of conservation status, and a key to differentiate these species. Results presented here reduce the number of native Linum species present in Mexico, modify the distribution range of others, provide data about conservation, as well as new records, and support the presence of the genus Hesperolinon in Mexican territory.

Linum schiedeanum Chamisso & Schlechtendal (1830a: 234). (Fig. 10b). Type:— MEXICO. Veracruz: in sylvaticis prope Jalapam, San Andrés, C. J. W. Schiede y F. Deppe 517 (C. J. W. Schiede s.n.) (holotype WU!, isotypes MO!, HAL!). Linum coulterianum Planchon (1848a: 498). Type:— MEXICO. Hidalgo: Zimapan, T. Coulter 758 (holotype K!, isotype GH!). Linum greggii Engelmann (1852a: 26). Cathartolinum coulterianum Small (1907d: 76). Cathartolinum schiedeanum (Schltdl. & Cham.) Small (1907d: 76). Cathartolinum greggii Small (1907e: 77). Type:— MEXICO. Coahuila: near Saltillo, Gregg 387 (holotype MO!, isotypes GH!, NY). Description: — Herbs, perennial, 10–70 cm in height, glabrous or almost glabrous, root thick; stems erect or extended, striate, unbranched to the inflorescence, glabrous. Leaves, basal ones entire, arranged in whorls of 4; distal ones ciliate, rarely opposite; oblanceolate to lanceolate, narrowly elliptical to obovate; 5.0–28.0 × 1.0–8.0 mm, sessile; apex acute, apiculate or mucronate; (1)3-nerved, midnerve conspicuous, occasionally also some lateral nerves; membranous, glabrous, or rarely with a few hairs near the base; stipular glands present at the base. Inflorescence a cymose panicle, pedicels 0.1–2.0 mm long; bracts 2.0–3.0 mm long, glabrous, margin glandular-dentate, apex acuminate, stipular glands absent; sepals persistent, lanceolate to ovate-lanceolate, 2.0–5.0 × 1.0– 1.5 mm; margin widely scariose, glandular-dentate; apex acute to cuspidate; 1–3-nerved, midnerve evident; stipular glands absent; petals yellow-green, oblanceolate or narrowly obcordate, 2.0–10.0 × 2.0–6.0 mm, sparsely pilose at the base; stamens 2.0–5.0 mm long; anthers 0.3–0.7 mm long, yellow; staminodia minute; styles free, 1.5–4.0 mm long; stigmata capitate, yellow. Fruit ovoid, light yellow, 1.4–5.0 × 3.0–4.0 mm, glabrous, pericarp thin, apex acute, dehiscent into 10 segments, false septa partially developed, septa with sparse marginal cilia; seeds ovate, reddish-brown, 1.0–2.0 × 0.6–1.0 mm. Distribution: — United States of America; in Mexico, in Chiapas, Mexico City, Coahuila, State of Mexico, Guanajuato, Hidalgo, Michoacan, Nayarit, Nuevo Leon, Oaxaca, Puebla, Queretaro, San Luis Potosi, Tamaulipas, Veracruz, and Zacatecas (Fig. 5b). Habitat and ecology: —Oyamel fir forest, deciduous forest, cypress-juniper forest, chaparral shrubland, crassirosette-leaved thorny shrublands, crop land, oak forests, oak-pine forests, thorny shrubland with lateral thorns, thornless or sub-thornless small-leaved shrublands, palm-tree forests, pine forests, grasslands, high or medium subdeciduous tropical forest, low deciduous forest, zacatonal alpine grasslands. Elevation 450–2950 m. Acrisol, Andosol, Cambisol, Kastanozem, Phaeozem, Fluvisol, Gleysol, Lithosol, Luvisol, Planosol, Regosol, Rendzina, Xerosol, and Vertisol soil types. Phenology: —Flowering and fruiting in June–February. Note: — Linum schiedeanum can be easily confused with L. nelsonii, since the latter varies in pubescence, size, and dimensions of leaves and flowers. However, among the characters that can be cited to differentiate L. schiedeanum include leaf width and glabrous pedicels and fruits. Conservation status: — Linum schiedeanum is a species with a wide distribution range and thrives in a great diversity of environments. According to the criterion and subcriteria B established by the IUCN (2019), this species can be considered as LC (EOO = 677,472.147 km 2 and AOO = 264 km 2,> 10 localities known). Specimens examined: — MEXICO. Chiapas: Amatenango, 5 km al este de la cabecera de Amatenango, 1676 m, 9 March 1988, J. López P. 339 (CHAPA!); Comitán, Al SW de Comitán atrás fraccionamiento Tenam, 1695 m, 16°15’17”N, 92°13’42”W, 4 September 2008, F. Hernández N. 2492 (XAL!); Oxchuc, 3 km S Rancho El Cura, 1970 m, 16°42’08”N, 92°15’52”W, S. Ochoa-Gaona et al. 4163 (CHAPA!); Oxchuc, Barrio Santisima Trinidad, 2050 m, 17 May 1988, F. Gómez S. 183 (MEXU!); San Juan Cancuc, Cruz ajk te´, 14 February 1992, J. Brett 824 (XAL!). Mexico City: Xochimilco, Xochitepec, 2250 m, 6 November 1977, A. Ventura A. 3150 (CIIDIR!, IBUG!). Coahuila: Artega, Puerto San Lorenzo, Cerro La Campana, 2460 m, 2 August 1979, L. Arce 10432 (ANSM!); Arteaga, Ejido El Puerto, 6 km de Los Lirios, 2520 m, 21 May 1980, R. López-Aguillón & J.A. Villarreal 664 (ANSM!, CHAP!); Arteaga, Ejido El Puerto, 2520 m, 27 May 1980, R. López A. & J.A. Villarreal 706 (ANSM!, CIIDIR!); Arteaga, Las Vigas Cañón de Jamé Sierra de Arteaga, 25°20’00”N, 100°39’00”W, 15 September 1988, J.A. Villarreal & M.A. Carranza 4581 (ANSM!); Arteaga, Las Vigas Cañón de la Carbonera, Sierra de Arteaga, 2600 m, 25°20’00”N, 100°39’00”W, 5 June 1987, J.A. Villarreal & M.A. Carranza 3758 (ANSM!); Arteaga, La Siberia Sierra de la Marta, 2300 m, 25°12’00”N, 100°30’00”, 27 May 1982, J.A. Villarreal 1656 (ANSM!); Arteaga, El Morro Sierra de Arteaga, 2900 m, 25°12’00”N, 100°16’00”, 25 September 1991, J.A. Villarreal & M.A. Carranza 6273 (ANSM!); Arteaga, Puerto San Lorenzo, Cerro La Campana, 2460 m, 2 August 1979, L. Arce s.n. (CHAPA!); Arteaga, Sierra de Zapalinamé, 2400 m, 27 June 1990, Hinton et al. 20411 (IEB!); Candela, Sierra Pájaros Azules Campo Santa María, 1800 m, 27°01’00”N, 100°50’00”W, 28 May 1997, P. Cruz A. 19 (ANSM!, CHAPA!); Candela, Sierra Pájaros Azules Campo Santa María, 1500 m, 27°02’00”N, 100°54’00”W, 5 December 1997, M.A. Carranza & D. Sánchez V. 2840 (ANSM!); Castaños, Sierra la Gavia Rancho La Gavia, 1500 m, 26°10’00”N, 101°18’00”W, 25 October 1995, J.A. Villarreal & M.A. Carranza 8362 (ANSM!); Castaños, Sierra la Gavia Rancho La Gavia, 1295 m, 26°10’00”N, 101°18’00”W, 10 August 1995, M.A. Carranza & J. Encinas 2262 (ANSM!); General Cepeda, Sierra Pilote de Fierro, 2950 m, 25°10’00”N, 101°25’00”W, 13 August 1993, M.A. Carranza et al. 1632 (ANSM!, CIIDIR!, MEXU!); Múzquiz, Río Sabinas al noroeste de Múzquiz, 453 m, 27°58’03”N, 101°34’28”W, 3 November 2005, J.A. Encina & I. Ramírez S. 1574 (ANSM!); Múzquiz, Carretera 53, Múzquiz-Boquillas, entrada al rancho la Babia, 980 m, 28°34’29”N, 102°03’27”W, 16 September 1999, J.A. Villarreal et al. 8866 (ANSM!); Múzquiz, Cañón Rincón de María en la Sierra de la Babia, 1450 m, 28°27’81.9”N, 102°04’50.7”W, 21 August 1999, M.A. Carranza et al. 3067 (ANSM!); Ocampo, Sierra Maderas del Carmen, 2270 m, 28°58’00”N, 102°35’00”W, 10 August 2004, D. Riskind et al. 23794 (ANSM!); Ocampo, Sierra del Pino, ejido Acebuches, 1850 m, 28°15’00”N, 102°59’00”W, 12 October 1991, M.A. Carranza et al. 901 (ANSM!, CIIDIR!, XAL!); Ocampo, Rancho La Cruz, 2000 m, 27°15’00”N, 102°40’00”W, 11 September 1991, M.A. Carranza & L. García S. 1176 (ANSM!, CIIDIR!, IBUG!); Ocampo, Sierra Maderas de Carmen, 2050 m, 28°59’00”N, 102°35’00”W, 31 July 1974, T. Wendt & A. Adamcewicz 443 (CHAPA!); Ocampo, 5 km al SW de Buenavista, 1650 m, 17 September 1981, J.L. Blando N. 8109145 (INEGI!); Escobedo, Las Vacas, 1600 m, 3 August 1958, C.A. Ely 195 (XAL!); Parras, Sierra de Parras en el arroyo seco del Rancho El Tunal, 2050 m, 1 September 1981, A. Rodríguez & P. Antonio H. 398 (ANSM!); Parras, Cañón de Gustrola, 1950 m, 25°20’00”N, 102°03’00”W, 14 October 1983, A. Rodríguez & M.A. Carranza 1259 (ANSM!, XAL!); Progreso, Rancho “Campo Santa María”de Cementos Mexicanos, 585 m, 27°05’38”N, 100°53’56”W, 4 November 2007, J.A. Encina & G. Rocha G. 2262 (ANSM!); Saltillo, Camino al Cerro El Penitente, 2710 m, 25°21’03”N, 100°54’47”W, J.A. Encina et al. 1488 (ANSM!); Saltillo, 300 m al oeste del Ejido Chapultepec, 2220 m snm, 25°14’40”N, 100°50’43”W, 6 July 2016, J.A. Encina et al. 5548 (ANSM!); Saltillo, Camino del Cuatro, Sierra de Zapalinamé, 1964 m, 25°21’58”N, 100°57’18”W, 19 March 2004, M.A. Llanas et al. 230 (CIIDIR!); Saltillo, Sierra de Zapalinamé, cañón de San Lorenzo, 2060 m, 25°23’00”N, 101°00’00”W, 03 August 1995, M.A. Carranza & J. Encinas 2229 (ANSM!, CIIDIR!, MEXU!); Saltillo, Sierra de Zapalinamé 3.15 km al noreste del ejido Cuauhtémoc, 2484 m, 25°17’33.48”N, 100°54’58.11”W, 30 August 2014, J.A. Encina et al. 4099 (ANSM!); Saltillo, Cañón de Timones al oeste de la Sierra de Zapalinamé, 2064 m, 25°19’47.36”N, 101°00’46.08”W, 26 April 2015, J.A. Encina & S. Guillermo R. 4554 (ANSM!); Saltillo, Sierra de Zapalinamé Cañón el Coyote, 2262 m, 25°21’28”N, 100°56’51”W, 19 August 2000, J.A. Encina et al. 575 (ANSM!); Saltillo, Camino del Cuatro Sierra de Zapalinamé, 1968 m, 27°58’03”N, 101°34’28”W, 1 November 2003, E. Padilla V. 1142 (ANSM!, MEXU!); Saltillo, Sierra de Zapalinamé Cañón de Santa Rosa-los Aguajes, 2400 m, 25°19’38”N, 100°57’46”W, 27 June 2000, J.A. Encina et al. 712 (ANSM!); Saltillo, Cañón de San Lorenzo, 1800 m, 13 September 1979, L. Arce & J.A. Villarreal 554 (ANSM!); Villa Acuña, Sierra del Carmen Canyon de Sentenela, 8 July 1936, F. Lyle W. & C.H. Mueller 583 (ANSM!); State of Mexico: Villa Nicolás Romero, Libertad, 2200 m, 10 September 1978, A. Ventura A. 3313 (INEGI!). Guanajuato: 3 km al W de Pozos, 2300 m, 28 June 1987, Rzedowski 43488 (XAL!). Hidalgo: Jacala, km 276 carretera México – Jacala, 1700 m, 30 October 1966, L.M.V. de Puga 15118 (IBUG!). Michoacan: Coalcomán, al S de Torrecillas, 1950 m, 18°48’25.66”N, 103°02’17.41”W, 21 December 1938, Hinton et al. 12805 (MEXU!). Nayarit: Xalisco, Cerro Boludo, al W de Xalisco, 1600 m, 20 February 1989, R.E. González & S. Aguilar 697 (UAMIZ!). Nuevo Leon: Aramberri, Puerto Carretas, 24 June 1981, O. Briones 714 (ANSM!); Dr. Arroyo, 7 km al S de La Encantada, 2520 m, 23°36’00”N, 99°50’00”W, 18 November 1993, J.A. Villarreal & M.A. Carranza 7681 (ANSM!); Santiago, Áreas cercanas a Cola de Caballo, 800 m, 25°23’00”N, 100°10’00”W, 10 October 1984, J.A. Villarreal et al. 2999 (ANSM!, XAL!); Santiago, Sierra Rancho Nuevo, 25°24’00”N, 100°28’00”W, M.A. Carranza et al. 1797 (ANSM!); Santiago, Laborcitas 15 km al oeste de V. de Santiago, 1400 m, 18 August 1976, V. Valdez T. 988 (INEGI!); Santiago, Cola de Caballo, 9 May 1979, J.A. Villareal 17217 (XAL!). Oaxaca: Ixtlán de Juárez, Carretera Ixtlán-Capulalpam km 7.1, 2000 m, 17°19’1.3”N, 96°26’5.59”W, 25 August 2002, S. Figueroa-Brito & F.Y. Guzmán-Rivera 139 (MEXU!). Puebla: Palmar de Bravo, Cerro Tepoxtla de San Martín Esperilla, 2500 m, 18°44’17.15”N, 97°32’23.49”W, 5 May 1992, P. Tenorio L. 18283 (MEXU!). Queretaro: Cadereyta, 5 km al S de Vizarrón, 2300 m, 16 August 1989, Rzedowski 48673 (CIIDIR!); Landa, 7 km al W de Tilaco, 1050 m, 9 June 1986, R. Fernández N. 3392 (IEB!); Landa, al N del parador Santa Martha, 1750 m, 30 November 1988, E. Carranza 1224 (IEB!); Landa, 1 km al Puerto de Malpaís, 1820 m, 13 June 1988, E. Carranza 588 (IEB!); Landa, 1 km al SW de El Lobo, 1600 m, 1 August 1987, Rzedowski 44023 (XAL!); Landa, 1 km al Sureste de El Pemoche, 1320 m, 2 May 1989, H. Rubio 626 (XAL!); 7 km por la brecha a Tres Lagunas y Valle de Guadalupe, 2000 m, 2 July 1987, H. Díaz-Barriga 3819 (IBUG!). San Luis Potosi: Guadalcázar, Matehualilla Sierra La Trinidad, 1920 m, 22°42’7.7”N, 100°28’44.1”W, 16 October 2005, O. Mares A. & M. Sosa M. 663 (ANSM!); Real de Catorce, Cerro La Cuchilla, 1920 m, 9 October 1979, J. García P. et al. 1309 (CHAPA!). Tamaulipas: Gómez Farias, Vecinity of “La Perra”, 1950 m, 18 June 1982, G. Diggs & M. Nee 2370 (XAL!). Veracruz: cerro al N del poblado de Jalcomulco, 19°20’40”N, 96°45’00”W, 20 November 1991. G. Castillo C & P. Moreno 7051 (XAL!); En el cerro, al N del poblado de Jalcomulco, 19°20’10”N, 96°44’50”W, 20 November 1991. G. Castillo C & P. Moreno 7448 (XAL!); Jalcomulco, 3 km antes de Jalcomulco por la Carr. Tuzamapa-Jalcomulco, 700 m, 19°22’00”N, 96°47’00”W, 15 January 1983, G. Castillo C. & A.P. Vovides 2765 (XAL!); Jalcomulco, Cerro del Brujo, 19°19’54”N, 96°45’42”W, 10 January 1992, G. Castillo C. & P. Zamora C. 8801 (XAL!); Jalcomulco, Cerro del Brujo, 19°19’54”N, 96°45’42”W, 10 January 1992, G. Castillo C. & P. Zamora C. 8789 (XAL!); Naolinco, Carr. Jalapa-Naolinco, 3 km antes de Naolinco, 1550 m, 29 June 1977, J.J. Fay & J.I. Calzada 729 (XAL!). Zacatecas: Susticacán, Sierra de los Cardos a 4 km al noroeste de la comunidad de Los Cuervos, 2230 m, 22°38’28.6”N, 103°11’53.6”W, 22 August 2019, L. Hurtado-Reveles 135 (CHAPA!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 172-173, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Chamisso, L. K. A. & Schlechtendal, D. F. L. (1830 a) Linum schiedeanum. Linnaea 5: 234.","Planchon, J. (1848 a) Linum coulterianum. London Journal of Botany 7: 498.","Engelmann, G. (1852 a) Linum greggii, Linum rupestre var. cymolosum. Smithsonian Contributions to Knowledge 3: 26.","Small, J. K. (1907 d) Cathartolinum coulterianum, Cathartolinum rupestre, Cathartolinum schiedeanum, Cathartolinum wrightii. North American Flora 25: 76.","Small, J. K. (1907 e) Cathartolinum cruciate, Cathartolinum greggii. Cathartolinum muelleri, Cathartolinum tenellum. North American Flora 25: 77.","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)"]}

Linum nelsonii Rose (1906: 117) (Fig. 7c). Type:— MEXICO. Veracruz: municipality of Orizaba, Boca del Monte, E. W. Nelson 210 (Holotype: US!). Description: — Herbs, perennial, occasionally annual, 17–65 cm in height, glabrous or sparely pubescent, root thin; stems erect to decumbent, commonly unbranched up to the inflorescence, essentially glabrous. Leaves, basal entire or ciliated, arranged in whorls of 4–6; distal glandular-dentate, alternate or opposite, ovate to obovate; 4.0–18.0(– 21.0) × 2.0–12.0 mm, decreasing to the inflorescence, sessile, apex obtuse to rounded or acute in distal leaves; 3–5- nerved, central nerve prominent; smooth, glabrous or with scattered pubescence, stipular glands present at the base. Inflorescence a cymose panicle, pedicels 3.0–12.0 mm long, rarely pubescent, whitish hairs; bracts 3.5–10.0 mm long, margin denticulate, apex acuminate, stipular glands present at the base; sepals persistent, lanceolate to narrowly lanceolate or narrowly ovate, 2.5–4.0 × 1.0–2.0 mm, margin glandular-dentate, apex acute to acuminate; 1–(3)-nerved, central nerve prominent; sparsely pubescent, occasionally with stipular glands present at the base; petals yellow-green, oblanceolate to obovate, 3.0–5.0 mm long, glabrous; stamens 2.0–4.0 mm long, villous at the base; anthers 0.6–1.0 mm long, light yellow; staminodia small; styles free, 1.7–4.0 mm long; stigmata capitate, yellow. Fruit widely ovoid, yellow, 1.4–2.0 × 1.5–2.0 mm, pericarp thin, apex acute pubescent, dehiscent into 10 segments, false septa partially developed, septa occasionally with marginal cilia; seeds oblong to ovate, reddish-brown, 0.8–1.3 × 0.5–0.7 mm. Distribution: —In Mexico, in Chiapas, Coahuila, Guanajuato, Hidalgo, Nayarit, Nuevo Leon, Oaxaca, Puebla, Queretaro, San Luis Potosi, Tamaulipas, and Veracruz (Fig. 2b); to Guatemala, Honduras, and Nicaragua. Habitat and ecology: —Deciduous forest, cypress-juniper forest, oak forests, oak-pine forests, chaparral shrubland, mangrove forest, thorny shrubland, thornless or sub-thornless small-leaved shrubland, pine forests, low deciduous tropical forest, medium or low evergreen tropical forest. Elevation 550–2400 m.Andosol,Acrisol, Cambisol, Phaeozem, Lithosol, Luvisol, Regosol, Rendzina, Vertisol, and Xerosol soil types. Phenology: —Flowering in February–November; fruiting in April–November. Note: —According to Rzedowski & Calderón de Rzedowski (1994), the type locality is probably in the state of Puebla. Although L. nelsonii is frequently confused with L. schiedeanum, L. nelsonii can be consistently differentiated from the latter by its pubescent pedicels and stipular glands present at the base of bracts and occasionally in sepals. Conservation status: —Although according to the criterion B2 established by the IUCN (2019), L. nelsonii can be considered as endangered because of presenting an AOO of 80 km 2, its EOO (496,346.970 km 2) exceeds the value necessary for a threatened category. Therefore, this species is LC given its wide distribution and number of known localities inside and outside the country. Specimens examined: — MEXICO. Chiapas: Comitán, km17, carretera Comitán, 3 Lagunas, 1781 m, 16°17’39”N, 92°15’59”W, 2 September 2008, G. López V. 1230 (XAL!); Oxchuc, Tz´unun, a 3 km de la escuela por el lado sur, 2400 m, 13 March 1988, F. Gómez S. 19 (MEXU!); Oxchuc, 8 km al norte de Oxchuc, 2400 m, 12 May 1988, F. Gómez S. 164 (MEXU!). Coahuila: Castaños, Sierra La Gavia, 1295 m, 26°10’00”N, 101°18’00”W, 10 August 1995, M.A. Carranza y J. Encinas 2261 (ANSM!); Castaños, Sierra La Gavia, 1500 m, 26°10’00”N, 101°18’00”W, 25 October 1995, J.A. Villarreal & M.A. Carranza 8363 (ANSM!); Ramos Arizpe, Sierra de La Paila, 1600 m, 25°58’00”N, 101°32’00”W, 2 November 1988, J.A. Villarreal et al. 4739 (ANSM!). Guanajuato: San Luis de la Paz, La Ventana, cerca de Mesas de Jesús, 2000 m, 24 March 1990, E. Ventura & E. López 7837 (XAL!). Hidalgo: Molango, 5-6 km al N de Ismolintla, 1900 m, 20°46’37.23”N, 98°43’59.95”W, 27 April 1981, R. Hernández et al. 5893 (MEXU!). Nayarit: Tepíc, 5 km de la desviación al Rancho La Noria, 1500 m, 21°29’00”N, 104°59’00”W, J.I. Calzada et al. 19192 (XAL!). Puebla: Oriental, Zautla, 2000 m, 6 August 1986, F. Ventura A. 22272 (XAL!). Nuevo Leon: Galeana, Ca. 13 miles SW of Galeana, 2200 m, 24°43’00”N, 100°12’00”W, 10 September 1999, Henrickson & V. Heuvel 22472B (ANSM!); Santiago, Cola de Caballo, 9 May 1979, J.A. Villarreal 2463 (ANSM!). Oaxaca: Eloxotitlán de Flores Magón, Alrededores del Puente de Fierro, 1175 m, 18°09’11.8”N, 96°51’11.7”W, 9 March 2001, Munn-Estrada et al. 856 (TEX!). Queretaro: Arroyo Seco, 6 km al E de la Florida, 1260 m, 21°25’48”N, 99°42’06”W, 13 April 2007, S. Zamudio et al. 13698 (IEB!); Jalpan de Serra, 4-5 km al SE de San Juan de los Durán, 1850 m, 24 May 2012, E. Carranza G. 7670 (ANSM!); Jalpan de Serra, Cañada en la ladera O del Cerro Grande, 2110 m, 21°25’56”N, 99°08’46”W, 29 March 2012, G. Aguilar-Gutiérrez et al. 854 (IEB!, XAL!); Jalpan de Serra, 4-5 km al sur de La Parada, 1200 m, 18 December 1991, B. Servín 1481 (IEB!); Jalpan de Serra, 2-3 km al poniente de El Saucito, 900 m, 13 March 1991, B. Servín 882 (IEB!); Landa, 2 km al S de El Rincón, 900 m, 2 April 1987, Rzedowski 42916 (XAL!); Pinal de Amoles, 2 km al S de San Pedro Escanela, 1740 m, 22 February 1991, E. Carranza 3035 (IEB!); Pinal de Amoles, 1.5-2 km al W de San Pedro Escanela, 1780 m, 17 April 1990, E. Carranza 2438 (IEB!); Pinal de Amoles, Cerca de Huazmazontla, 1300 m, 12 March 1989, Rzedowski 48399 (XAL!). San Luis Potosi: El Naranjo, Vicinity El Salto above El Naranjo, 446 m, 22°35’11.79”N, 99°23’0.59”W, 1 April 1960, J.A. Duke 3675 (MEXU!). Sinaloa: Concordia, 4.5 km al SE de La Petaca, 1700 m, 12 February 2000, R. Vega-Aviña & J.A. Gutiérrez-García 10554 (MEXU!). Tamaulipas: Hidalgo, Into the Sierra 14.9 mi W of Hotel Santa Engracia, 570 m, 24°01’00”N, 99°34’00”W, 17 April 1988, G. Nesom 6339 (XAL!). Veracruz: Huiloapan, Cerro de San Cristóbal, 1300 m, 18°48’00”N, 97°03’00”W, 22 April 1982, J.I. Calzada 8592 (XAL!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 160-161, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Rose, J. N. (1906) Linum longipes. Linum nelsonii. Contributions from the United States National Herbarium 10: 117.","Rzedowski, J. & Calderon de Rzedowski, G. (1994) Linaceae. In: Universidad Nacional Autonoma de Mexico (Ed.) Flora del Valle de Tehuacan-Cuicatlan. Fasciculo 5: 1 - 15. [ISBN: 968 - 36 - 3875 - 5]","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)"]}

Linum aristatum Engelmann (1848: 101). (Fig. 3a). Type:— MEXICO. Chihuahua: Near Carizal south of El Paso, Wislizenus 101 (holotype MO!, isotype GH!). Cathartolinum aristatum Small (1907a: 83). Mesynium aristatum (Engelm.) W.A.Weber (1984: 3). Description: — Herbs, annual, 10–45 cm in height, glabrous, main root thick; stems extended, ascending, rigid, broomshaped, striate, branched from the base, glabrous. Leaves entire, alternate; basal leaves sometimes opposite; linear, (4.8)5.0–20.0 × 0.3–1.1 mm, sessile; apex acute to acuminate, tip whitish to translucent; 1-nerved, membranous, glabrous; stipular glands present at the base, black. Inflorescence a cymose panicle, pedicels thin, 6.2–34.0 mm long; bracts 5.5–9.0 mm long, apex acuminate, margin glandular-dentate, stipular glands absent; sepals deciduous, linearlanceolate, scariose, 6.4–7.5 mm long, glandular-dentate, apex smoothly attenuated; 3-nerved, central nerve evident; without stipular glands; petals yellow to yellow-orange, obovate, 8–12 mm long, glabrous; stamens 5–7 mm long, glabrous; anthers elliptical, 0.7–1.1(1.2) mm long, yellow; staminodia absent; styles fused to near the apex, 4.5–7.0 mm long; stigmata capitate, yellow. Fruit ellipsoid, yellow, clearly longer than wide, 3.5–4.0 × 2.5–3.0 mm, glabrous, pericarp thin, apex obtuse, dehiscent into 5 segments; seeds elliptical, dark brown, 2.5–3.0 × 0.8–1.0 mm. Distribution: — United States of America; in Mexico, in Chihuahua, Coahuila, and Tamaulipas (Fig. 2a). Habitat and ecology: —Cypress-juniper forest, oak forests, oak-pine forests, thornless or sub-thornless smallleaved shrubland, grasslands, pine forests, vegetation of sandy arid deserts. Elevation (300) 1100–3100 m. Dry sandy soils of the Phaeozem, Lithosol, Luvisol, Regosol, Vertisol, and Xerosol types. Phenology: —Flowering in March–August; fruiting in August–November. Note: — Linum aristatum is easily distinguished from the rest of the species with dehiscence into 5 segments for having pale ellipsoid fruits and thin pericarp, in addition to narrow and smoothly attenuated sepals. Conservation status: —According to IUCN Red List Categories and Criteria (IUCN 2019), L. aristatum is EN (B1 + 2ab(iii)), with an EOO et al. 2014). Specimens examined: — MEXICO. Chihuahua: Along hiway 45, 112 miles N of Gallego, 1250 m, 18 July 1975, K.L.Wallace et al. 136 (ENCB!); Juárez, 4.8 miles S of Samalayuca, 1275 m, 31°18’00”N, 106°29’00”W, 19 August 1971, J. Henrickson 5780 (MEXU!); Juárez, 5 km N of Samalayuca, 1250 m, 31°24’30”N, 106°27’36”W, 28 October 1972, T.L. Wendt et al. 9922 (MEXU!). Coahuila: Gravelly mesas near Díaz, 742 m, 29°10’24.81”N, 101°36’0.97”W, 17 April 1900, C.G. Pringle 8312 (MEXU!). Tamaulipas: Nuevo Laredo, Sandy upland fourteen miles south of Nuevo Laredo, 141 m, 27°20’25.11”N, 99°36’19.33”W, 24 March 1944, N.T. Heard & F.A. Barkley 14604 (MEXU!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on page 147, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Engelmann, G. (1848) Linum aristatum. Memoir of a Tour to Northern Mexico 101.","Small, J. K. (1907 a) Cathartolinum aristatum. North American Flora 25: 83.","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)","Fernandez, J. A., Hafner, M. S., Hafner, D. J. & Cervantes, F. A. (2014) Conservation status of rodents of the families Geomyidae and Heteromyidae of Mexico. Revista Mexicana de Biodiversidad 85: 576 - 588. https: // doi. org / 10.7550 / rmb. 36710"]}

Linum scabrellum Planchon (1848d: 507). (Fig. 11). Type:— MEXICO. Hidalgo: Zimapán, T. Coulter 754 (holotype K!). Cathartolinum scabrellum Small (1907c: 74). Linum macradenium Brandegee (1911: 181). Type:— MEXICO, San Luis Potosi, Minas de San Rafael, Purpus 4923 (holotype UC!, isotype F, GH!, MO!, US). Description: — Herbs, perennial, up to 50 cm in height, pubescent to densely pubescent, root thick; stems erect, ascending, striate, branched from the base, sometimes simple, covered with rigid, whitish, conspicuous hairs. Leaves entire, occasionally with marginal glands in the upper leaves; basal leaves opposite, distal leaves alternate; linear, linearlanceolate, inferior leaves occasionally elliptical, 5.0–17.0 × 1.0– 3.5 mm, sessile, apex acute to acuminate, 1-nerved, coriaceous, pubescent; black stipular glands present at the base, very conspicuous. Inflorescence a cymose panicle, pedicels (5.9)10.0–20.0 mm long; bracts 2.5–7.1 mm long, pubescent along the central nerve, margin glandular-dentate, apex acuminate; black stipular glands present at the base, very conspicuous; sepals persistent, lanceolate to narrowly ovate, 2.5–5.5(6.0) × 1.0– 2.2 mm, margin glandular-dentate; apex acute to acuminate, occasionally with purple hues; 3-nerved, central nerve evident; stipular glands two, black, present at the base, very conspicuous; petals yellow-orange, oblanceolate, 4–10 mm long, pilose at the base; stamens 4–7 mm long, glabrous or sparsely pilose; anthers 0.4–1.2 mm long, yellow; staminodia minute, sometimes absent; styles free, 2.5–6.5 mm long; stigmata capitate, yellow. Fruit ovoid to subglobose, yellow, 2.5 × 2.5–4.0 mm, glabrous, pericarp thick, apex acute, dehiscent into 10 segments, false septa partially developed, septa ciliated; seeds elliptical to ovate, reddish-brown, 1.5–2.0 × 1.0 mm. Distribution:—Endemic to Mexico, in Aguascalientes, Guanajuato, Hidalgo, Nuevo Leon, Oaxaca, Puebla, Queretaro, San Luis Potosi, and Veracruz (Fig. 5c). Habitat and ecology: —Cypress-juniper forest, cardonal shrublands, chaparral shrubland, crassi-rosette-leaved thorny shrublands, oak forest, oak-pine forest, yucca shrublands, thorny shrubland, thornless or sub-thornless smallleaved shrubland, pine forests, grasslands, low deciduous tropical forest, low deciduous thorny tropical forest, sandy arid desert vegetation. Elevation 1400–2950 m. Cambisol, Kastanozem, Phaeozem, Fluvisol, Lithosol, Luvisol, Regosol, Rendzina, Vertisol, and Xerosol soil types. Phenology: —Flowering in March–December; fruiting in June–December. Note: —This is the only species in Mexico that is pubescent throughout all its vegetative parts, with no leaves in whorls and with free styles. It is morphologically similar to L. rupestre, but the latter is entirely glabrous. It was observed that the specimens of L. scabrellum collected in localities further north of its distribution range are slightly less densely pubescent than those from central and southern Mexico; it is possible that Rzedowski and Calderón de Rzedowski (1992) refer to this character when they describe these plants as “ cinereas ” (i.e. whitish-looking). Conservation status: — Linum scabrellum is a species with a wide distribution range and according to the criterion B and subcriteria established by the IUCN (2019), this species can be considered as LC (EOO = 186,173.234 km 2). However, taking into account its AOO of 140 km 2 and the expansion of mining and ranching activities in its distribution area (Salinas-Rodríguez 2015, De Nova et al. 2019), the species could see its populations threatened in the short term. Specimens examined: — MEXICO. Aguascalientes: Tepezalá, Extremo NE deArroyo Hondo, 2000m, 22°11’05”N, 102°11’13”W, 1 November 2007, G. García 5386 (IEB!); Tepezalá, 4 km al E de Tepezalá, 2247 m, 22°13’13.1”N, 102°08’6.1”W, 19 April 2013, G. García R. 6015 (INEGI!). Guanajuato: Atarjea, Puerto del Gallo, 8 km al Sureste de La Joya, 2100 m, 14 December 1988, E. Ventura & E. López 6501 (XAL!); San Luis de la Paz, 5 km al S de Pozos, 2100 m, 24 September 1994, Rzedowski 52586 (ANSM!, XAL!); San Luis de la Paz, cerca de El Pregón, 24 September 1994, Rzedowski 52569 (IEB!, XAL!); 3 km al W de Pozos, 2300 m, 28 June 1987, Rzedowski 43481 (XAL!). Hidalgo: Nicolás Flores, El Arenalito, 20°46’04”N, 99°68’56”W, 20 September 1995, V.H. López B. 134 (CHAP!, XAL!). Nuevo Leon: Aramberri, Cerro Grande, 2180 m, 19 October 1986, Hinton et al. 19106 (CHAPA!, CIIDIR!, IEB!); Dr. Arroyo, Carretera Matehuala-Dr. Arroyo aprox. 38 km, 17 June 1992, J.A. Villarreal & M.A. Carranza 6555 (ANSM!); Dr. Arroyo, Santa Gertrudis, nr., 1780 m, 16 March 1993, Hinton et al. 22707 (ANSM!); Dr. Arroyo, Camino a Agua Nueva, 2000 m, 23 June 1981, O. Briones 683 (ANSM!, XAL!); Galeana, Santa Gertrudis, 1700 m, 20 July 1993, Hinton et al. 23043 (IEB!); Mier y Noriega, West of Refugio de Cerros Blancos, 1825 m, 1 October 2001, Hinton et al. 27692 (ANSM!). Oaxaca: Cuicatlán, 6 km al N de Cuicatlán, 1750 m, 19August 1987. A. Salinas T. et al. 4323 (XAL!); 2 km al NE-E de Suchixtlahuaca, 2100 m, 17°43’00”N, 97°21’00”W, 6 June 1985, F. Chiang et al. 2519 (MEXU!, XAL!). Puebla: Cañada Otate, brecha a Hijaderoaria, 2121 m, 18°01’00”N, 97°20’00”W, 5 November 2001, P. Tenorio L. & L. Kelly 21561 (MEXU!); Hwy 28, N of Azumbilla (which is N of Tehuacan), 2375 m, 18°41’00”N, 97°24’20”W, 16 July 1991, Mayfield et al. 876 (MEXU!). Queretaro: Peña Miller, Ejido Maguey Verde, 2242 m, 21°05’21”N, 99°41’45”W, 13 October 2005, O. Mares A. & M. Sosa M. 497 (ANSM!); Cadereyta, Alrededores de Maconí, 1800 m, 10 November 1988, Rzedowski 47642 (ANSM!); Ezequiel Montes, Cerro La Caja frente a la Peña de Bernal, 2157 m, 20°44’38.2”N, 99°55’49.3”W, 24 September 2020, J. González-Velasco & P. Albarrán-González 20001 (CHAPA!); San Joaquín, Cañada La Culebra, 1600 m, 27 August 1978, S. Zamudio 3221 (CIIDIR!); 5 km al S de Vizarrón, 16 August 1989, Rzedowski 48673 (CIIDIR!); Cadereyta, Alrededores de Maconí, 1800 m, 10 November 1988, Rzedowski 47642 (IBUG!); San Joaquín, Cañada La Culebra, 1600 m, 27 August 1978, S. Zamudio R. 3221 (IBUG!, XAL!); Tequisquiapan, 3 km al W de Las Rosas, 2000 m, 8 September 1990, Rzedowski 49998 (XAL!); Ezequiel Montes, 7.5 km de Bernal, carretera a Tolimán, 2000 m, 20°46’22”N, 99°54’14”W, 11 October 2008, E. Carranza & I. Silva 7493 (IEB!); Peñamiller, Camargo, 1700 m, 12 June 1991, E. Ventura & E. López 9229 (IEB!); Ezequiel Montes, 7.5 km de Bernal, carretera a Tolimán, 2000 m, 20°46’22”N, 99°54’14”W, 11 October 2008, E. Carranza & I. Silva 7493 (UAMIZ!); Peñamiller, Camargo, 1700 m, 12 June 1991, E. Ventura & E. López 9229 (XAL). San Luis Potosi: Ahualulco, 9.7 km al W del entronque Ahualulco-Charcas, 2100 m, 10 October 1985, F. García-Pérez 2025 (ANSM!, INEGI!, SLPM!); Armadillo de los Infante, Sierra de Álvarez, 1800 m, 1 September 2012, F. García S. 8640 (ANSM!, SLPM!); Armadillo de los Infante, Camino a Tlaxcalilla a 200 m del cruce con la carretera con dirección a la mina, 1711 m, 22°16’0.67”N, 100°40’13.6”W, 10 September 2020, A. Villalvazo-Hernández & J. González-Velasco 44 (CHAPA!); Charcas, 6 km al E de Miguel Hidalgo, 23°12’00”N, 101°04’00”W, 7 July 1985, P. Tenorio L. & T.P. Ramamoorthy 9208 (MEXU!); Guadalcazár, Km 9 carretera a Guadalcazár, 1635 m, 22°37’19.3”N, 100°29’26”W, 11 September 2020, A. Villalvazo-Hernández & J. González-Velasco 49 (CHAPA!); Guadalcázar, 1.6 km al este de la carretera Matehuala-San Luis Potosí, 1609 m, 9 November 2019, V.W. Steinmann & M.M. Salinas-Rodríguez 8249 (CHAPA!); Guadalcázar, El Cañón Hondo, 12 km al NW de Guadalcázar, 22°36’58”N, 100°29’21”W, 16 November 1996, R. Torres C. 14852 (IEB!); Guadalcazár, El Cañón Hondo, 12 km al NW de Guadalcazár, 22°36’58”N, 100°29’21”W, 10 October 1996, R. Torres C. 14698 (IEB!); Real de Catorce, 18 km del entronque Matehuala-San Luis Potosí, 1850 m, 23°50’00”N, 101°05’00”W, 5 June 1990, J.A. Villarreal et al. 5734 (ANSM!, IBUG!); Real de Catorce, Camino a Real de Catorce sobre la loma que está antes de entrar al pueblo, 2537 m, 23°26’26.5”N, 100°48’59”W, 12 September 2020, A. Villalvazo-Hernández & J. González-Velasco 52 (CHAPA!); Real de Catorce, Parte alta del cerro Quemado, 2910 m, 23°40’21”N, 100°54’45”W, 25 August 2013, S. Zamudio R. 16411 (IEB!); Soledad Diez Gutiérrez, 5 km al NE de Laguna Seca, 2000 m, 30 August 1955, Rzedowski 6293 (SLPM!); Villa Guadalupe, Sierra del Catorce rumbo a los lomeríos, 1833 m, 23°26’26.5”N, 100°48’59.6”W, 12 September 2020, A. Villalvazo-Hernández & J. González-Velasco 51 (CHAPA!); Villa Juárez, Camino Guaxcamá-Buenavista con dirección a la mina, 1215 m, 22°15’49.6”N, 100°39’38”W, 11 September 2020, A. Villalvazo-Hernández & J. González-Velasco 45 (CHAPA!). Veracruz: Perote, ladera de cerro, 2400 m, 19°33’47.17”N, 97°13’47.17”W, 19 December 1998, G. Castillo-Campos 19095 (MEXU!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 170-171, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Planchon, J. (1848 d) Linum scabrellum. London Journal of Botany 7: 507","Small, J. K. (1907 c) Cathartolinum catharticum. Cathartolinum pringlei. Cathartolinum scabrellum. North American Flora 25: 74.","Brandegee, T. S. (1911) Linum macradenium. University of California Publications in Botany 4: 181.","Rzedowski, J. & Calderon de Rzedowski, G. (1992) Linaceae. In: Rzedowki, J. & Calderon de Rzedowski, G. (Eds.) Flora del Bajio y de Regiones Adyacentes. Fasciculo 6: 1 - 22. [ISBN: 0188 - 5170]","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)","Salinas-Rodriguez, M. M. (2015) Conocimiento, manejo y conservacion de la diversidad floristica de la Sierra Madre Oriental, Mexico. Universidad Autonoma de Nuevo Leon. Mexico. PhD Thesis, pp. 242."]}

Linum cruciata Planchon (1848b: 499). (Fig. 3d) Type:— MEXICO. Nayarit: Tepic, Sinclair s.n. (holotype K!). Cathartolinum cruciata Small (1907e: 77). Linum gracilentum M.E. Jones (1929: 148). Type:— MEXICO. Nayarit: Tepic, M.E. Jones 22882 (isotypes GH, UC, US!). Description: — Herbs, perennial, 15–50 cm in height, essentially glabrous, root thin; stems decumbent toward the base, branched from the base, glabrous in the basal part; pilose in the distal part, near nodes and the inflorescence. Leaves, basal ones entire, arranged in whorles of 4; distal ones dentate, alternate, widely ovated or elliptical, 5.4–13.8 × (3.2) 3.3–8.3 mm, sessile or subsessile, petiole villous; apex obtuse to subacute, apiculate; 1-nerved, more evident on the abaxial surface; slightly scariose, glabrous, or sparsely pilose, stipular glands present at the base. Inflorescence a cymose panicle, with extended branches, pedicels villous, (1.5)3.0–6.0 mm long; bracts 1.9–4.3 mm long, margin dentate, with pedunculate glands, apex acute, stipular glands present, black; sepals persistent, lanceolate, sometimes quite narrow, (1.8)2.4–3.0 × 0.4–0.8 mm, margin with conspicuous glandular teeth, apex acute to subacuminate, 3- nerved, central nerve evident, glabrous; petals light yellow, 4.0–6.0 mm long, glabrous; stamens 3.0–4.0 mm long; anthers 0.7–1.2 mm long, light yellow; staminodia minute; styles free, 2.5–4.3 mm long; stigmata capitate, yellow. Fruit widely ovoid, yellow, (1.1)1.3–1.7 × 1.1–2.0 mm, sparsely pilose above the middle portion, pericarp thin, apex acute, dehiscent into 10 segments, false septa poorly developed; seeds widely ovate, brown, 0.8–0.9 × 0.7–0.8 mm. Distribution: —In Mexico, in Durango, Jalisco, Nayarit, Queretaro, Sinaloa, Sonora, and Tamaulipas (Fig. 5a). Habitat and ecology: —Deciduous forest, oak forests, oak-pine forests, pine forests, high evergreen tropical forests, low deciduous tropical forest, low thorny deciduous tropical forest, low subdeciduous tropical forest. Elevation 1300–1900 m. Cambisol, Lithosol, Regosol, Vertisol, and Xerosol soil types. Phenology:—Flowering and fruiting in March–July. Note: —Endemic to Mexico. It is the only species of the genus within its distribution area that has a combination of characters including leaves in whorls and sepals with conspicuous glandular teeth. In addition, L. cruciata presents free styles and short and villous pedicels, which allow differentiating it from L. longipes. Conservation status: —Although L. cruciata has an EOO of 315,975.629 km 2, its distribution is not continuous, affecting the extent of occurrence of this species. Based on an AOO of 28 km 2 and the number of localities known (Specimens examined: — MEXICO. Durango: Canelas, 1200 m al Norte de Canelas, 5 March 1986, M. Vizcarra 265 (CHAP!, CHAPA!, CIIDIR!, IBUG!, IEB!, MEXU!, UAMIZ!); Steep side canyons of the RíoTamazula, 1300 m, 20 March 1972, D.E. Breedlove 24527 (ENCB!). Jalisco: Autlán, Sierra de Manantlán, 1900 m, 19°32’00”N, 104°14’00”W, 23 March 1965, R. McVaugh 23219 (ENCB!). Nayarit: Tepíc, near Tepíc, 1588 m, 21°29’18.31”N, 104°56’0.16”W, 5 January 1892, E. Palmer 2013 (US!). Queretaro: Jalpan, a 5 km al SE de Jalpan, 1400 m, 1 May 1982, P. Tenorio & R. Hernández 316 (MEXU!). Sinaloa: Capadero, Sierra Tacuichamona, 12 february 1940, H.S. Gentry 5583, 5585 (MEXU!). Sonora: Alamos, Entre San Bernardino y Chinipas, 1250 m, 27°19.3’00”N, 108°44’00”W, 18 March 1992, G. Ferguson et al. s.n. (ARIZ!). Tamaulipas: 3 km al Sureste de Puerto Purificación, 2 June 1990, F. González M. et al. 17402 (MEXU!); 7 km al Sureste de Puerto Purificación, 6 June 1990, F. González M. et al. 17467 (MEXU!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on page 151, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Planchon, J. (1848 b) Linum cruciata. London Journal of Botany 7: 499.","Small, J. K. (1907 e) Cathartolinum cruciate, Cathartolinum greggii. Cathartolinum muelleri, Cathartolinum tenellum. North American Flora 25: 77.","Jones, M. E. (1929) Linum gracilentum. Contributions to Western Botany 15: 148."]}

Linum rzedowskii Arreguín (1985: 262). (Fig. 10a). Type:— MEXICO, State of Mexico: Llano Pinahua, approximately 8 km SW from Rio Frío, municipality of Ixtapaluca, 3200 m, in a clearing in the middle of the pine forest, J. Rzedowski 37285 (holotype ENCB!). Description: — Herbs, perennial, 15–25 cm in height, glabrous, root thick; stem creeping or prostrate, slightly striate, branched from the base, glabrous. Leaves entire, alternate, linear-lanceolate, (3.0–)4.6–5.5(–10.0) × (1.0–)1.1–1.3(– 2.0) mm, sessile, apex acuminate; 1–3-nerved, central nerve evident; coriaceous, glabrous, stipular glands absent. Inflorescence racemose, pedicels (4.5) 6.9–10.6 mm long, glabrous; bracts 2.1–4.2 mm long, margin entire, apex acute, stipular glands absent; sepals persistent, ovate, 3.0–4.0 × 2.0–3.0 mm, shorter than the capsule; margin white, scariose; apex acute; 1-3 nerved, barely evident lateral nerves; glabrous, stipular glands absent; petals blue, obovate, 6.0–8.0(11) mm long, glabrous; stamens 2.4–4.2 mm long; anthers 0.6–1.0 mm long, yellow; staminodia minute; styles free, 1.1–1.9 mm long; stigmata capitate, yellow. Fruit ovate, yellow, 5.0–6.0 × 4.0–5.0 mm, glabrous, pericarp thick, apex acute, dehiscent into 10 segments; septa ciliate; seeds elliptical, brown, 3.0–4.0 × 1.2–1.5 mm. Distribution: —Endemic to Mexico, in the State of Mexico (Fig. 5b). Habitat and ecology: —Grasslands, pine forests, low deciduous tropical forest. Elevation 3000–3500 m.Andosol, Cambisol, Phaeozem, Planosol, Regosol, and Vertisol soil types. Phenology: —Flowering and fruiting in July–August. Note: —This blue-flowered species occurs only in a small area of the State of Mexico; its distribution does not overlap that of L. lewisii. The creeping habit, the white margins of sepals, and the size of petals support an easy differentiation. Conservation status: —Although, according to the B1 criterion established by the IUCN, L. rzedowskii can be considered Critically Endangered (CN) (EOO = 24 km 2), due to its AOO of 24 km 2 and a number of known localities, together with the degradation of its habitat adjacent to the largest human population nuclei by deforestation and tourism (Pineda-Jaimes et al. 2009, CONABIO 2021), this species is considered EN (B1 + 2abc(iii)). Specimens examined: — MEXICO. State of Mexico: Chalco, Río Frío Estación Forestal Zoquiapan, 3500 m, 16 August 1974, E. García M. et al. 1256 (CHAPA!); Ixtapaluca, Estación Experimental de Investigación y Enseñanza de Zoquiapan 8 km al S de Río Frío, 3250 m, 04 July 1975, S.D. Koch 75289 (CHAP!, CHAPA!); Ixtapaluca, Estación Experimental de Investigación y Enseñanza de Zoquiapan 8 km al S de Río Frío, 3000 m, 28 August 1975, S.D. Koch & J. Magaña M. 75471 (CHAPA!); Ixtapaluca, Estación Experimental de Investigación y Enseñanza de Zoquiapan 8 km al S de Río Frío, 3200 m, 30 October 1975, S.D. Koch 75704 (CHAPA!); Ixtapaluca, Estación Experimental de Investigación y Enseñanza de Zoquiapan 8 km al S de Río Frío, 3200 m, 3 July 1978, R. Vega A. 229 (CHAPA!); Ixtapaluca, Llano Pinahua, 3250 m, 12 August 1980, Rzedowski 36790 (CIIDIR!, IEB!, SLPM!); Ixtapaluca, Llano Grande, 3000 m, 30/August/1983, E. Ventura V. 1295 (IEB!, XAL!); Ixtapaluca, Llano Tepochaico, 3350 m, 17/July/1983, Rzedowski 38109 (IEB!, XAL!); Ixtapaluca, Llano Grande, 3100 m, 3 July 1983, E. Ventura V. 1051 (UAMIZ!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 169-170, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Arreguin, S. M. L. (1985) Una nueva especie de Linum (Linaceae) del Valle de Mexico. Phytologia 57: 261 - 266.","Pineda-Jaimes, N. B., Bosque-Sendra, J., Gomez-Delgado, M. & Plata-Rocha, W. (2009) Analisis de cambio del uso del suelo en el Estado de Mexico mediante sistemas de informacion geografica y tecnicas de regresion multivariantes: Una aproximacion a los procesos de deforestacion. Investigaciones Geograficas 69: 33 - 52.","CONABIO (2021) Indice de Impacto Humano en la Biodiversidad Terrestre. Comision Nacional para uso y conocimiento de la Biodiversidad. Available from: http: // geoportal. conabio. gob. mx / metadatos / doc / html / indihum 14 gw. html (accessed 1 December 2021)"]}

Linum berlandieri var. filifolium (Shinners) C.M. Rogers (1984a: 39). (Fig. 3c). Type:— UNITED STATES OF AMERICA. Texas: Brewster County, McVaugh 7798 (holotype SMU, isotypes F, GH!, MICH). Linum rigidum var. filifolium Shinners (1949: 136). Description: — Herbs, annual, occasionally perennial, 5–40 cm in height, hirsutulose near the base; root thin; stems erect, extended, ascending, striate, branching from the base, essentially glabrous, hirsutulose at the base. Leaves entire or distal leaves with few tiny marginal teeth, basal leaves opposite or alternate, distal leaves alternate; linear to linearlanceolate, (4.5)10.0–25.0 × (0.5)1.0–4.0 mm, the largest near or above the middle part of the stem; sessile, apex acuminate, 3-nerved, scariose, glabrous, stipular glands small present at the base. Inflorescence a cymose panicle, dense, pedicels 2.8–4.5 mm long, striate; bracts 3.8–6.3 mm long, margin with few minute teeth, apex acuminate, whitish, stipular glands at the base; sepals deciduous, lanceolate, (4.9)6.0–12.0 × 1.2–1.5 mm, margin with prominent glandular teeth, sometimes scariose; apex acute or attenuated, usually 3-nerved, glabrous, stipular glands absent; petals yellow-orange, reddish to brick-red below the middle portion, widely obovate, 11.0–19.0 mm long, glabrous; stamens 4.0–9.0 mm long; anthers 1.0–2.0 mm long, yellow; staminodia absent; styles fused to near the apex, 6.0–9.0 mm long, yellow; stigmata capitate, dark brown. Fruit widely ovoid to triangular-ovoid, yellow, 3.6–4.7 × 3.0–4.0 mm, pericarp thin, translucent, apex obtuse, dehiscent into 5 segments; seeds narrowly ovate, reddish-brown, 2.6–3.4 × 1.0– 1.6 mm. Distribution: — United States of America; in Mexico, in Chihuahua, Coahuila, and Nuevo Leon (Fig. 2a). Habitat and ecology: —Cypress-juniper forest, crassi-rosette-leaved thorny shrubland, oak forests, yucca forests, thornless or sub-thornless small-leaved shrubland, evergreen thorny tropical forest. Elevation 200–1750 m. Sandy, rocky soils, sometimes calcareous belonging to Kastanozem, Phaeozem, Lithosol, Planosol, Regosol, Rendzina, and Xerosol. Phenology:—Flowering and fruiting in March–June. Note: —Only this variety is distributed in Mexico. The presence of bracts with a whitish acuminate apex and the capsular fruit with thin, somewhat translucent pericarp, allows separating L. berlandieri var. filifolium from L. berlandieri var. berlandieri. Conservation status: —According to the criteria established by the IUCN (2019) and its distribution in a few northern states of Mexico, L. berlandieri var. filifolium is EN (B1 + 2ac(iii)) with an EOO Specimens examined: — MEXICO. Chihuahua: Manuel Benavides, Sierra Rica arroyo El Pedregoso, 1743 m, 29°10’12”N, 104°02’58”W, A. Juárez P. 165 (MEXU!, SLPM!). Coahuila: Villa Acuña, Serranias del Burro Rcho El Bonito, 29°01’30”N, 102°07’30”W, 4 May 1981, D.H. Riskind 2362 (ANSM!); 2.5 km of Rancho El Jardin on the road toward Mina El Popo, 1600 m, 29°07’00”N, 102°40’00”W, 28 July 1973, M.C. Johnston et al. 11840 (MEXU!); 5.2 rd miles NW of Rancho El Jardin towars Mina Popo, 1645 m, 29°09’00”N, 102°43’00”W, 2 July 1973, J. Henrickson & B. Prigge 11460 (MEXU!); 17 miles S of Allende along Hwy 57, 500 m, 28°12’00”N, 101°05’00”W, 3 May 1977, J. Henrickson & E. Lee 16025 (MEXU!); 22 km ESE of La Cuesta del Plomo on the Múzquiz-Boquillas highway, 1000 m, 28°38’38”N, 102°18’18”W, 7 June 1972, F. Chiang et al. 7543 (MEXU!); 52 miles SE of Big Bend National Park basin in the S end of the Sierra Maderas del Carmen in Cañon del Alamo, 1450 m, 28°52’00”N, 102°34’00”W, 5 August 1976, J. Henrickson & B. Prigge 14916 (MEXU!). Nuevo Leon: Hwy. 85, ca. 4 mi. SW of Nuevo Laredo, 14 November 1958, R.C. Rollins & R.M. Tryon 5802 (MEXU!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 149-151, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Rogers, C. M. (1984 a) Linum berlandieri var. filifolium. North American Flora, series 2, 12: 39.","Shinners, L. H. (1949) Linum rigidum var. filifolium. Field & Laboratory 17: 136.","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)"]}

Linum tenellum Chamisso & Schlechtendal (1830b: 235). (Fig. 10c). Type:— MEXICO. Veracruz: Near Jalapa, C. J. W. Schiede & F. Deppe 518 (holotype HAL!, syntype HAL!, WU). Cathartolinum tenellum Small (1907e: 77). Description: — Herbs, annual, occasionally perennial, 8–50 cm in height, densely pubescent; hairs whitish, conspicuous; root thin; stems erect to decumbent, striate, commonly unbranched up to the inflorescence, pubescent. Leaves glandulardentate; basal leaves arranged in whorls of 4; distal leaves alternate, rarely opposite; elliptical to obovate toward the base, lanceolate to oblanceolate or oblong toward the distal part; 3.0–13.0 × (1.4)1.5–5.0 mm, gradually decreasing toward the inflorescence; sessile, apex acute to obtuse, 1-nerved; slightly membranous, pubescent; stipular glands present at the base. Inflorescence a cymose panicle, sparsely branched; pedicels 2.0–10.0 mm long; bracts 2.1–3.4 mm long, pubescent, margin glandular-dentate, apex acute, stipular glands present at the base of the lower bracts; sepals persistent, lanceolate to ovate, 1.9–3.0 × (0.8) 1.2–1.5 mm, margin glandular-dentate, apex acute, 3-nerved, pubescent or only along veins, stipular glands absent; petals yellow, obovate, 2.0–6.0 mm long, glabrous; stamens 2.0–3.0 mm long, sparsely pubescent at the base; anthers up to 1 mm long, light yellow; staminodia present, occasionally absent; styles free, 1.7–2.5 mm long; stigmata capitate, light yellow. Fruit ovoid, yellow with purple hues on the upper portion, 1.5–3.0 × 1.2–1.8 mm, sparsely pubescent, apex acute, puberulent or glabrous, dehiscent into 10 segments, false septa incompletely developed, septa without marginal cilia; seeds elliptical or ovate, brown, 1.0–1.2 × 0.5–0.7 mm. Distribution: —Endemic to Mexico, in Chiapas, Queretaro, San Luis Potosi, Tamaulipas, and Veracruz (Fig. 5a). Habitat and ecology: —Deciduous forest, oak forests, oak-pine forests, grasslands, and high or medium subevergreen tropical forest. Elevation 750–2200 m. Andosol, Cambisol, Phaeozem, Lithosol, Luvisol, Regosol, Vertisol, and Xerosol soil types. Phenology:—Flowering and fruiting in April–December. Note: — Linum tenellum is the only species in the genus that has leaves in whorls and that is densely pubescent throughout, with more stiff and conspicuous hairs, these being characters that support an accurate identification. Conservation status: —According to the IUCN criteria (IUCN 2019), L. tenellum is VU (B1 + 2ac(iii)). This species has an EOO of 6,180,759 km 2 and an AOO of 28 km 2, and is known from L. tenellum as a species in danger of extinction. Specimens examined: — MEXICO. Chiapas: La Independencia, Lake shore of Montebello, 1588 m, 16°06’16.81”N, 91°41’23.2”W, 2 May 1945, A.J. Sharp 45453 (MEXU!). Queretaro: Arroyo Seco, Aprox. 3 km de San Juan Buenaventura, 1460 m, 8 December 1988, E. Carranza 1236 (IEB!); Landa, 2 km al SO del Madroño, 1720 m, 8 May 1989, E. González 550 (IEB!, MEXU!). San Luis Potosi: Rioverde, Parque Nacional El Potosí, 2187 m, 1 March 2018, A.K. Gudiño-Cano et al. 646 (SLPM). Tamaulipas: Piedra Iman, 2 km al ESE de Sn. José, Sierra Sn. Carlos, 790 m, 24°40’30”N, 90°06’00”W, 22 November 1984, O. Briones 1245 (ANSM!). Veracruz: Atzalan, La Florida, 1700 m, 2 April 1976, F. Ventura A. 12609 (SLPM!, XAL!); Coacoatzintla, Coacoatzintla, 1200 m, 14 May 1973, F. Ventura A. 8294 (IEB!, XAL!); Miahuatlán, 5 km al SE de la Colonia Reforma, 1750 m, 19°43’00”N, 56°51’00”W, 24 April 1979, J.I. Calzada 5331 (XAL!); Tonayan, Desviación de Tonayán, 1600 m, 1 June 1981, M. Chazaro B. 156 (XAL!).

Linum elongatum (Small) H.J.P.Winkler (1931: 116). (Fig. 6a). Type:— UNITED STATES OF AMERICA. Texas: Laredo, Reverchon 3776 (originally cited as Bush 3776) (holotype NY!, isotypes MO, US!). Cathartolinum elongatum Small (1907f: 82). Description: — Herbs, annual, occasionally perennial, 15–30 cm in height, glabrous, root thick; stems erect to ascending, striate, branched from the base, branches diffuse, glabrous. Leaves entire, sometimes glandular, alternate, linear, 5.0–25.0 × 0.5–1.0(1.5) mm, sessile, apex acute; 1-nerved, nervation more evident in the abaxial surface, scariose; glabrous, stipular glands present, sometimes only at the base of distal leaves. Inflorescence a cymose panicle, pedicels 5.2–10.4 mm long; bracts 3.2–6.3 mm long, margin dentate, apex acuminate, with stipular glands present at the base; sepals deciduous, lanceolate, 6.0–11.0 × 1.4–1.8 mm, margin glandular-dentate, apex attenuate, 3-nerved, stipular glands absent; petals yellow-orange to salmon or brownish-red, wine-red base, widely obovate, 14.0–18.0 mm long; stamens 5.0–6.0 mm long; anthers 1.5–2.5 mm long, brick-red; staminodia absent; styles fused to near the apex, 7.0– 9.5 mm long; stigmata capitate, gray to wine-red. Fruit ovoid, yellow, 4.0–4.3 × 3.0– 3.7 mm, glabrous, pericarp thick, apex obtuse, dehiscent into 5 segments; seeds narrowly elliptical, reddish-brown, 2.3–3.0 × 1.2–1.3 mm. Distribution: — United States of America; in Mexico, in Tamaulipas (Fig. 5b). Habitat and ecology: —Thorny shrubland. Elevation 0–300 m. Compact sandy soils, Xerosol type. Phenology: —Flowering in February–May; fruiting in March–August. Note: —In its habitat, during the flowering period, the species is easily recognized due to the color of its petals with their distinctive wine-red-colored band near the center, brick-red anthers and wine-red to gray stigmata, which together provide diagnostic characters. The stems of the species are strongly striate. Conservation status: — Linum elongatum is known only from a narrow area of Texas and northern Mexico. One locality is known from Mexico, in the state of Tamaulipas, which may suggest some vulnerability. With only these data, it is not possible to carry out a conservation assessment. Therefore, to explore its probable threat category, it was necessary to integrate the records of GBIF. According to the B criterion (IUCN 2019), this species is Near Threatened (NT). Thus, it presents an EOO close to 20,000 km ² (22,940.563 km 2) and AOO Specimens examined: — MEXICO. Tamaulipas: Nuevo Laredo, Along Hwy 2, 5 mi E of junction with Hwy 85, 28 August 1976, C.M. Rogers 13477 (CIIDIR!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 152-154, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Small, J. K. (1907 f) Cathartolinum elongatum. North American Flora 25: 82.","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)"]}

Key to Linaceae genera in Mexico 1. Petals with reddish venation, presence of basal adaxial appendages; carpels, styles, and stigmata 2 or 3; fruit dehiscent into 4 or 6 segments........................................................................................................................................................................ Hesperolinon - Petals without reddish venation, absence of basal daxial appendages; carpels, styles, and stigmata 5; fruit dehiscent into 5 or 10 segments.................................................................................................................................................................................... Linum, Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on page 143, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753

Linum Linnaeus (1753: 277). Type:— Linum usitatissimum L., N. Amer. Fl. 25: 67. 1907. Description:— Herbs, sometimes shrubs, annual or perennial; glabrous, puberulent, or pubescent partially or throughout; stems erect or extended, sometimes decumbent, unbranched or branched from the base or from the inflorescence, glabrous or pubescent. Leaves entire, dentate or glandular-dentate; alternate, opposite and/or in whorls; sessile or subsessile, with or without stipular glands. Inflorescence terminal, in cymose panicles or racemes, rarely in corymbs or solitary. Flowers with 5 sepals, imbricate, attached at the base, commonly persistent, rarely deciduous; entire, laciniate, ciliate, dentate, or glandular-dentate, glabrous or pilose; petals 5; yellow, white, pink, yellowishorange, orange, or blue, rarely red or crimson-brown; longer than sepals; stamens 5, provided with 5 small staminodia or absent; styles 5, free, connate at the base or fused up to 1/2 or more of the style length, filiform; stigmata capitate or straight; ovary superior, 5-locular or 10-locular for the presence of false septa. Fruit with septicidal capsule; ovoid, ellipsoid, or triangular-ovoid; dehiscent into 5 or 10 segments; glabrous or pilose; seeds 10, lenticular, flattened, elliptical to broadly elliptical; brown to reddish-brown; testa mucilaginous. The genus comprises 24 native and one introduced species distributed throughout the Mexican territory., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on page 146, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Linnaeus, C. (1753) Linum. Species Plantarum 1: 277."]}

Hesperolinon (A.Gray) Small, 1907h: 84. Type:— Hesperolinon californicum (Benth.) Small, N. Amer. Fl. 25: 86. 1907. Description: — Herbs, annual, thin, glabrous, occasionally pubescent or puberulent; stems erect or extended, sometimes slightly decumbent, not branched or branched from the base or from the inflorescence, glabrous or pubescent. Leaves entire or with marginal glands; basal leaves arranged in whorls of 4, distal leaves opposite or alternate; sessile or subsessile, with or without stipular glands. Inflorescence terminal, in a cymose panicle, sometimes condensed. Flowers with 5 sepals, imbricate, connate at the base, persistent, entire or with marginal glands, glabrous or villous; petals 5, yellow, white to pink, convolute, reddish venation; presence of basal adaxial appendages, more or less conspicuous, that sometimes expand into auricles; stamens 5, staminodia absent; styles 2–3, free, stigmata capitate or subcapitate; ovary superior, 2 or 3-locular, or 4 or 6-locular due to the presence of false septa. Fruit a septicidal capsule, ovoid, dehiscent into 4 or 6 segments, glabrous; seeds 4 or 6, triangular in cross-section, brown, often with darker spots; testa mucilaginous. The genus comprises one species in Mexico, distributed in a narrow area of the state of Baja California., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on page 143, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Small, J. K. (1907 h) Hesperolinon. North American Flora 25: 84."]}

Hesperolinon micranthum (A.Gray) Small, (1907i: 85.) (Fig. 1). Type:— UNITED STATES OF AMERICA. California: Mariposa County, Mt. Bullion, Bolander 4854 (holotype GH!, isotypes DS, UC!). Linum micranthum A. Gray (1868: 333). Description: — Herbs, 5–50 cm in height, glabrous to sparsely puberulent at the base; stems slightly decumbent, smooth, branched from the base, glabrous; stipular glands generally present at the base. Leaves entire, basal leaves in whorls, distal leaves alternate; linear or closely oblong, (5.5)10.0–20.0(–30.0) × (0.3)1.5–2.5(–3.0) mm; sessile, apex acute to obtuse, glabrous, stipular glands present only in basal leaves. Inflorescence in a cymose panicle, pedicels 3.9– 14.6(–30.0) mm long, sometimes longer in the fruit; bracts 0.9–1.3 mm long, margin entire, apex acute; sepals entire or with minute marginal glands, lanceolate, 1.0–3.0 × 0.6–0.9 mm, apex slightly acuminate, glabrous; petals white to light pink, oblanceolate, 1.5–3.5 mm long; stamens 1.5–2.5 mm long; anthers purple or dark purple, 0.3–1.0 mm long; styles 3, 0.5–1.0(–2.0) mm long, stigmata capitate; ovary 3 or 6-locular for the presence of false septa. Fruit yellow, 1.3–1.5 × 1.3–1.4 mm, pericarp thin, apex acute, dehiscent into 6 segments; seeds 6, 1.1–1.3 × 0.4–0.6 mm. Distribution: — United States of America; in Mexico, in northern Baja California (Fig. 2a). Habitat and ecology: — Cypress-juniper forest and chaparral shrubland. Elevation 50–2000 m. Common in serpentine soils in the California biogeographic province. Phenology: —Flowering and fruiting in May–October. Note: —Although the species is not endemic to Mexico, its distribution is restricted to the California biogeographic province (Delgadillo 1998, Morrone 2019). Hesperolinon micranthum is the only species in the genus reported (Springer 2009, Schneider et al. 2016, Jepson eflora 2019) and corroborated in this study, with a distribution range stretching to Mexico. According to the material reviewed, the species is clearly distinguished from the species in the genus Linum distributed in Mexico by the number of carpels, styles, and stigmata, as well as by the dehiscent fruit. Conservation status: —According to IUCN Red List Categories and Criteria (IUCN 2019), H. micranthum is Endangered (EN) (B1 + 2ac(iii)). Its extent of occurrence (EOO) is less than 5,000 km 2 (1,751.668 km 2) and its estimated area of occupancy (AOO) is 12 km 2. This species presents a restricted distribution, only known in Baja California in Mexico. Additionally, its habitat has been subjected to multiple anthropogenic pressures (Morrone 2019), and may face major risks. S pecimens examined: — MEXICO. Baja California: Ensenada, Rancho Caliente, 22 May 1971, I.L. Wiggins 21556 (ENCB!); Tecate, Cerro Jesús María, 770 m, 30°31’00’’N, 116°49’00’’W, 9 May 1970, R. Moran 17565 (ENCB!); Tecate, Cerro Matomí, 1300 m, 30°23’00’’N, 115°06’00’’W, 4 May 1973, R. Moran 20820 (ENCB!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 143-146, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Gray, A. (1868) Linum micranthum. Proceedings of the American Academy of Arts and Sciences 7: 333.","Delgadillo, J. (1998) Floristica y Ecologia del Norte de Baja California. Universidad Autonoma de Baja California, Mexico, pp. 407. [ISBN: 968 - 73 - 2677 - 8]","Morrone, J. J. (2019) Regionalizacion biogeografica y evolucion biotica de Mexico: encrucijada de la biodiversidad del Nuevo Mundo. Revista Mexicana de Biodiversidad 90: e 902980.","Springer, Y. P. (2009) Do extreme environments provide a refuge from pathogens? A phylogenetic test using serpentine flax. American Journal of Botany 96: 2010 - 2021. https: // doi. org / 10.3732 / ajb. 0900047","Schneider, A. C., Freyman, W. A., Guilliams, C. M., Springer, Y. P. & Baldwin, B. G. (2016) Pleistocene radiation of the serpentine-adapted genus Hesperolinon and other divergence times in Linaceae (Malpighiales). American Journal of Botany 103: 221 - 232. https: // doi. org / 10.3732 / ajb. 1500379","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)"]}

Linum australe A. Heller (1898: 627). (Fig. 3b). Type:— UNITED STATES OF AMERICA. New Mexico: 4 mi E of Santa Fe, Heller & Heller 3724 (holotype NY!, isotypes F!, GH!, K!, KANU, KSC, MO!, MSC, NEB, US!). Cathartolinum australe Small (1907b: 81). Linum aristatum var. australe (A.Heller) Kearney & Peebles (1939: 485). Mesynium australe (A.Heller) W.A.Weber (1984: 3). Description:— Herbs, annual, 10–55 cm in height, puberulent in the basal part, glabrous or almost glabrous in the distal part; root thin; stems erect, striate, usually branched from the base, glaucous, puberulent. Leaves entire, sometimes slightly glandular-dentate, involute, alternate, linear, 4.0–20.0 × 0.5–2.0 mm, sessile, apex acute to acuminate, tip whitish, 1-nerved, coriaceous, glabrous, stipular glands present. Inflorescence a cymose panicle, pedicels 2.0–15.0 mm long, striate; bracts (3.9)4.0–6.0 mm long; margin scariose, glandular-dentate; sometimes with purple spots, apex acute, stipular glands present or sometimes absent; sepals deciduous, linear-lanceolate, 4.0–6.0 × (0.9)1.0– 1.5 mm, margin glandular-dentate, occasionally with reddish-purple spots, apex cuspidate-aristate, tip whitish, 1(–3)-nerved, stipular glands present or absent; petals light yellow to yellow-orange, oblanceolate or obovate, 6.0– 100 mm long, stamens 3.0–7.0 mm long; anthers 0.5–1.0(1.1) mm long, yellow; staminodia absent; styles fused to near the apex, 2.0–6.0 mm long, stigmata capitate. Fruit ovoid, yellow, 3.0–3.2 × 2.4–4.0 mm, glabrous, pericarp thick, apex obtuse, dehiscent into 5 segments; seeds elliptical, reddish-brown, 2.0–3.0 × 0.8–1.0 mm. Distribution: — United States of America; in Mexico, in Baja California, Chihuahua, Coahuila, and Durango (Fig. 2b). Habitat and ecology: —Oyamel fir forest, oak forests, oak-pine forests, thorny shrublands, and pine forests. Elevation 1500–2700 m. Montane soils, mainly Andosol, Cambisol, Phaeozem, Fluvisol, Lithosol, Regosol, Rendzina, Vertisol, Xerosol, and Yermosol. Phenology: —Flowering and fruiting in August–September. Note: — Linum australe is the only species within its distribution range that is glabrous beyond the base, with yellow flowers and fused styles almost to the apex. The stems and pedicels strongly striated to sulcate in the distal part are a distinctive character of the species. Its distribution in the northern part overlaps with the distribution of L. aristatum; however, they can be differentiated, since the latter presents a much more branched habit, a glabrous stem, and an ellipsoid fruit with thin pericarp. Conservation status: —According to the criteria established by the IUCN (2019) this species is EN (B2ac(iii)) with an EOO of 512,558.866 km 2 and AOO of 16 km 2, and Specimens examined: — MEXICO. Baja California: Sierra San Pedro Mártir, canyon at base of Cerro Botella Azul, 2700 m, 19 July 1988, S. Boyd & A. Liston 2700 (MEXU!). Chihuahua: Road between Babicora and Yepomera, 2500 m, 8 April 1977, Bennett et al. 821 (CHAPA!). Coahuila: Acuña, 75 km al noroeste de Ciudad Acuña, 565 m, 29°34’56”N, 101°43’31”W, 29 May 2016, J. A. Encina et al. 5415 (ANSM!). Durango: Súchil, Hacienda El Mortero, 1970 m, 15 September 2001, N. Almaraz et al. 60 (CIIDIR!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 147-149, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Heller, A. A. (1898) Linum australe. Bulletin of the Torrey Botanical Club 25: 627. https: // doi. org / 10.2307 / 2478298","Small, J. K. (1907 b) Cathartolinum australe. North American Flora 25: 81.","Kearney, T. H. & Peebles, R. H. (1939) Linum aristatum var. australe. Journal of the Washington Academy of Sciences 29: 485.","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)"]}

Linum lewisii Pursh (1813: 210). (Fig. 6d). Type:— UNITED STATES OF AMERICA. Missouri: In the valleys of the Rocky Mountains and on the banks, M. Lewis s.n. (holotype PH!). Linum sibiricum var. lewisii (Pursh) Lindley (1828: 1163). Linum perenne var. lewisii (Pursh) Eaton & C.Wright (1840: 302). Linum perenne subsp. lewisii (Pursh) Hultén (1947: 1122). Adenolinum lewisii (Pursh) Á.Löve & D. Löve (1982: 348). Description: — Herbs, perennial, 5–80 cm in height, glabrous or nearly glabrous, root thick; stems erect, ascending, striate, branched near the base, glabrous. Leaves entire, alternate, linear to linear-lanceolate or linear-oblanceolate, 5.0–30.0 × 0.7–2.0(–4.5) mm, sessile, apex acute, 1-nerved, rough, glabrous, stipular glands absent. Inflorescence a cymose panicle, pedicels sparsely villous, 5.0–16.5(–20) mm long; bracts 3.2–6.4(8.0) mm long, margin entire, apex acute; sepals persistent, elliptical to elliptical-ovate, 2.6–5.0 × 1.8–3.7 mm; margin entire, scariose, whitish; apex acute; 1–3-nerved, stipular glands absent; petals blue, obovate, 6.0–15.0(–23.0) mm long; stamens 3.0–10.0 mm in length; anthers 1.0–1.7(–2.2) mm long, white; staminodia present, thin; styles free, 1.5–6.5(–12.0) mm long; stigmata capitate, light yellow. Fruit widely ovate, yellow, 4.6–7.0 × 4.4–6.8 mm, glabrous, pericarp thick, apex acute to apiculate, dehiscent into 10 segments; false septa partially developed, ciliate; seeds lanceolate-ovate, dark brown, 2.5–4.5 × 1.5–3.0 mm. Distribution: — United States of America; in Mexico, in Baja California, Chihuahua, Coahuila, Durango, Nuevo Leon, San Luis Potosi, Sonora, and Tamaulipas (Fig. 5a). Habitat and ecology: —Oyamel fir forest, cypress-juniper forest, crassi-rosette-leaved thorny shrublands, oak forests, yucca forests, thornless or sub-thornless small-leaved shrubland, grasslands, pine forests, low evergreen thorny tropical forest, deciduous forest, and thorny shrubland. Elevation 1500–3700 m. Cambisol, Kastanozem, Phaeozem, Lithosol, Luvisol, Planosol, Regosol, Rendzina, Vertisol, and Xerosol soil types. Phenology:—Flowering and fruiting in April–October. Note: — Linum lewisii can be confused with L. usitatissimum; however, the sepals shorter than the fruit with scariose whitish margins, a smaller bearing, and the capitate stigmata differentiate L. lewisii from the latter. Conservation status: —Although the AOO of this species is 76 km 2, the EOO (237,518.364 km 2) along with other subcriteria (IUCN 2019), such as a large number of environments where it occurs and the number of known localities inside and outside the country, make it possible to catalog L. lewisii as Least Concern (LC). Specimens examined: — MEXICO. Baja California: San Pedro Martír, Sierra de San Pedro Martír, 2560 m, 30°58’00”N, 115°25’00”W, 19 June 1985, R.F. Thorne et al. 60925 (MEXU!). Chihuahua: Madera, Colonia Chuhuichupa, 2240 m, 24 June 1990, A. Benítez 1382 (ANSM!, CHAP!, CIIDIR!, IEB!, UAMIZ!); Madera, Rancho La Ciénega, 2500 m, 31 August 1990, O. Bravo B. 1391 (CHAP!, CIIDIR!, UAMIZ!). Coahuila: Arteaga, Las Vigas Sierra de Arteaga, 2600 m, 25°20’00”N, 100°39’00”W, J.A. Villarreal & M.A. Carranza 3784 (ANSM!, CIIDIR!); Arteaga, Sierra de Los Lirios, 3600 m, 3 July 1943, E. Lyonnet 4003 (CHAP!, IEB!); Cerro San Pedro near N.L., 2200 m, 24°46’00”N, 100°47’30”W, 22 August 1974, T. Wendt et al. 627 (CHAPA!); Cima de Sierra La Marta, 3600 m, 25 October 1984, McDonald & Gómez 1247 (XAL!); Cima de Sierra La Viga, 3300 m, 25 October 1984, McDonald & Gómez 1211 (XAL!); Ramos Arizpe, Cañon del Carmen, 1400 m, 25°59’10”N, 101°28’30”W, 5 August 1975, M.F. Robert & J. Passini 4498 (ANSM!); Ramos Arizpe, Sierra de La Paila, 2000 m, 25°58’00”N, 100°25’00”W, 31 October 1987, J.A. Villarreal et al. 4156 (ANSM!); Ramos Arizpe, Cañon Loma Prieta, 1600 m, 25°51’00”N, 101°30’00”W, 23 October 1985, J.A. Villarreal et al. 3110 (ANSM!); Saltillo, Carretera 54 a 1 km al S de Guadalupe Victoria, 1950 m, 24°59’53”N, 101°04’84”W, 25 September 2013, F. Meraz et al. 108 (CIIDIR!); Saltillo. Sierra La Viga, 3700 m, 22 August 1986, McDonald 2087 (XAL!); Sierra Coahuilon, 3500 m, 18 June 1985, McDonald 1512 (XAL!); Sierra Coahuilon, 2500 m, 22 July 1985, McDonald 1725 (XAL!); Sierra de la Marta, 3580 m, 16 June 1985, McDonald 1433 (IBUG!, XAL!); Sierra Maderas del Carmen, 2250 m, 28°59’00”N, 102°36’30”W, 3 August 1974, T. Wendt & A. Adamcewicz 458 (CHAPA!). Durango: Pueblo Nuevo, El Salto, 2650 m, 23°47’26.2”N, 105°23’48.9”W, 1 September 1934, F.E. Pennel 18563 (MEXU!). Nuevo Leon: Cerro del Potosí, 3650 m, 21 June 1985, McDonald 1550 (XAL!); Cumbre de Cerro Potosí, 3600 m, 26 July 1985, McDonald 1780 (XAL!); Galeana, Cerro del Potosí, 3500 m, 16 May 1981, L. Arce et al. 1333 (ANSM!); Galeana, Rancho El Compromiso, 1600 m, 3 August 1999, E. Estrada C. 10553 (ANSM!); Galeana, Rancho Aguililla, 1885 m, 29 June 2000, Hinton et al. 27593 (ANSM!); Galeana, Cima del Cerro Potosí, 3670 m, 3 August 1988, A. García 61 (CHAP!, CIIDIR!); Galeana, Rancho Aguililla, 1850 m, 8 August 1990, Hinton et al. 20476 (CHAPA!); Galeana, Cima del Cerro Potosí, 3500 m, 4 August 1988, A. García 74 (CIIDIR!). San Luis Potosi: Charcas, Sierra de Monte Grande, 2300 m, 14 September 1989, J.A. Reyes A. 430 (CHAPA!). Sonora: Agua Prieta, Rancho Puerta Blanca (Cuenca Los Ajos Reserve), 1295 m, 31°18’57”N. 109°05’35”W, 23 March 2007, A.L. Reina & T.R. Van Devender 275 (MEXU!). Tamaulipas: Peña Nevada, 3600 m, 5 July 1985, McDonald 1618 (XAL!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 155-156, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Pursh, F. T. (1813) Linum lewisii. Flora Americae Septentrionalis 1: 210.","Lindley, J. (1828) Linum sibiricum var. lewisii. Botanical Register 14: 1163.","Hulten, O. E. G. (1947) Linum perenne subsp. Lewisii. Flora of Alaska and Yukon 7: 1122.","Love, A. & Love, D. B. M. (1982) Adenolinum lewisii. Taxon 31: 348. https: // doi. org / 10.1002 / j. 1996 - 8175.1982. tb 03587. x","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)"]}

Linum australe var. glandulosum C.M. Rogers (1964a: 336). (Fig. 4). Type:— MEXICO. Durango: Otinapa, Palmer 465 (holotype US!, isotypes F!, GH, MO!, NY!). Mesynium australe (C.M. Rogers) W.A.Weber (1984: 3). Description:— Herbs with black stipular glands, very prominent on nodes, base of all leaves, bracts, and sepals. Distribution: — United States of America; in Mexico, in Chihuahua, Mexico City, Durango, State of Mexico, Guanajuato, Puebla, Sonora, and Veracruz (Fig. 2b). Habitat and ecology: —Cypress-juniper forest, oak-pine forests, prickly-pear cactus patches, grasslands, oak forests, thornless small-leaved shrubland, and pine forests. Elevation 1500–2650 m. Montane soils, mainly red-ash Acrisol, Andosol, Cambisol, Phaeozem, Lithosol, Luvisol, and Regosol. Phenology: —Flowering and fruiting in May–September. Taxonomic note: —The black and prominent stipular glands of L. australe var. glandulosum on the nodes, leaves, bracts, and sepals make it possible to clearly differentiate this variety of the species. Conservation status: — Rzedowski & Calderón de Rzedowski (1992) mention that L. australe var. glandulosum is at risk of extinction. However, according to the criteria established by the IUCN (2019) this variety is Vulnerable (VU) (B2abc(iii)), with an EOO of 164,257.374 km 2 and AOO of 28 km 2, known to Specimens examined: — MEXICO. Chihuahua: Chuhuichupa, near Chuhuichupa, 2148 m, 29°36’36”N, 108°22’48”W, 1 August 1936, H. LeSueur 132 (MO!). Mexico City: Milpa Alta, Paraje de Cuauhte, 2650 m, 4 July 1976, A. Ventura A. 1727 (IEB!). Durango: Durango, 18 miles west of Durango, 24 July 1964, C.M. Rogers 13183 (MEXU!). State of Mexico: Ixtapaluca, Cerro del Pino, 2300 m, 1 November 1972, M.L. Arreguín 346 (MEXU!); Tlalmanalco, Tramo Tlalmanalco-Amecameca, 2260 m, 12 September 1976, J. García P. 199 (CHAPA!). Guanajuato: León, 41 km al NE de León, 2450 m, 14 July 1987, J. Rzedowski 43752 (IEB!). Puebla: Acatzingo, San Juan Ocozoc, 2110 m, 18°59’00”N, 97°47’00”W, 1 July 1907, G. Arsené 1921 (MEXU!). Sonora: Yecora, 0.2 km north of Yecora and road to Agua Blanca, 1540 m, 28°22’46”N, 108°55’37”W, 15 July 1997, A.L. Reina et al. 780 (MEXU!). Veracruz: Perote, Sierra entre Mastaloyan y Frijol Colorado, 2650 m, 19°38’00”N, 97°23’00”W, 25 August 1984, G. Castillo C. et al. 3288 (XAL!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on page 149, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Rogers, C. M. (1964 a) Linum australe var. glandulosum. Sida 1: 336.","Rzedowski, J. & Calderon de Rzedowski, G. (1992) Linaceae. In: Rzedowki, J. & Calderon de Rzedowski, G. (Eds.) Flora del Bajio y de Regiones Adyacentes. Fasciculo 6: 1 - 22. [ISBN: 0188 - 5170]","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)","CONABIO (2021) Indice de Impacto Humano en la Biodiversidad Terrestre. Comision Nacional para uso y conocimiento de la Biodiversidad. Available from: http: // geoportal. conabio. gob. mx / metadatos / doc / html / indihum 14 gw. html (accessed 1 December 2021)","Rodriguez-Echeverry, J. & Leiton, M. (2021) Perdida y fragmentacion de ecosistemas boscosos nativos y su influencia en la diversidad de habitats en el hotspot Andes tropicales. Revista Mexicana de Biodiversidad 92: e 923449. https: // doi. org / 10.22201 / ib. 20078706 e. 2021.92.3449"]}

Linum longipes Rose (1906: 117). (Fig. 7a). Type:— MEXICO. Guerrero: In mountains near Iguala, Pringle 9261 (holotype US!, isotypes GH!, MICH!, MSC). Description: — Herbs, annual, thin, 22–34 cm in height; glabrous, except for a few short hairs near the nodes and the base of branches; root thin; stems erect, simple, unbranched to the middle part, essentially glabrous. Leaves entire; basal leaves arranged in whorls of 4, obovate; distal leaves alternate, ovate; (5.3)14.0–18.0 × (2.5)7.5–9.0 mm, petioles 0.1–1.0(2.0) mm long, apex obtuse; 1-nerved, prominent on the abaxial surface; slightly rough, glabrous; stipular glands present at the base, but not well developed. Inflorescence a widely open cymose panicle occupying half or more of the plant height, pedicels 7.0–17.0 mm long; bracts 2.0- 2.8 mm long, margin entire, apex acute-acuminate, stipular glands absent; sepals persistent, ovate, 2.0–2.5(2.7) × 0.8–1.2 mm, margin entire or with minute glands, apex acuminate, 3-nerved, stipular glands absent; petals yellow, obovate, 4.0 mm long, glabrous; stamens 3.0–4.0 mm long; anthers 0.4 mm long, light yellow; staminodia present; styles fused to near the apex, 1.7–2.3 mm long; stigmata capitate, yellow. Fruit widely ovoid, light yellow, 1.8–1.9 × 1.2–1.9 mm, glabrous, pericarp thin, apex apiculate, dehiscent into 10 segments, false septa incomplete with some marginal hairs; seeds elliptical, light brown, whitish cover, 0.4-0.6 × 1.0– 1.1 mm. Distribution: —Endemic to Mexico, in Guerrero, Morelos, and Puebla (Fig. 2a). Habitat and ecology: —Oak forests, low deciduous tropical forest. Elevation 700–1600 m. Cambisol, Lithosol, and Rendzina soil types. Phenology:—Flowering and fruiting in October. Note: — Linum longipes shares a similar morphology with L. cruciata; however, when reviewing the herbarium material, longer pedicels, glabrous, and fused styles are observed as unequivocal characters of L. longipes. Besides, the species shows the unique trait of a few minute hairs near all nodes and at the base of branches. Conservation status: — Linum longipes has an EOO of 416.473 km 2 and an AOO of 16 km 2. In addition to being endemic, the species is known from Specimens examined: — MEXICO. Guerrero: Iguala, Mountains near Iguala, 1514 m, 18°22’46.23”N, 99°28’25.71”W, 11 October 1900, C.G. Pringle 9261 (MEXU!). Morelos: Jojutla, Cerro del Higuerón, 750 m, 14 October 1984, I. Rivera 25 (MEXU!, UAMIZ!). Puebla: Izúcar de Matamoros, 2 October 1942, F. Miranda 2222 (MEXU!); Izúcar de Matamoros, Tropical Deciduous Forest at Puerto Las Palmas, 1525 m, 12 October 1986, D.E. Breedlove & F. Almeda 65221 (MEXU!); Izúcar de Matamoros, Carretera Izúcar-Huajuapan de León, 1300 m, 18°31’33”N, 98°25’05”W, 30 October 1994, J.L. Panero et al. 5302 (MEXU!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 156-157, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Rose, J. N. (1906) Linum longipes. Linum nelsonii. Contributions from the United States National Herbarium 10: 117.","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)"]}

Linum flagellare H.P.J. Winkler (1931: 116). (Fig. 6b). Type:— MEXICO. Coahuila: Parras, Purpus 1122 (holotype NY!, isotypes F, GH!, MO!, UC). Cathartolinum flagellare Small (1907g: 78). Linum coahuilense C.M. Rogers (1964b: 279). Type:— MEXICO. Coahuila. 10 mi W of Saltillo, Correll & Johnston 21403 (LL!). Description: — Herbs, perennial, 25–40 cm in height, glabrous, glaucous, root thick; stems erect, more or less branched throughout, glabrous. Leaves entire, alternate, basal leaves sometimes opposite, linear to linear-lanceolate, (5.0)11.0– 17.0 × (0.5) 0.7–1.7 mm, sessile, apex slightly acuminate, 1-nerved, coriaceous, glabrous; stipular glands generally absent, sometimes present only in basal leaves. Inflorescence a cymose panicle, more or less diffuse, branches thin, pedicels 2.1–8.3 mm long; bracts 2.2–2.7 mm long, margin entire, apex acuminate; sepals persistent, narrowly lanceolate, 2.0–5.6 × 0.9–1.3 mm; margin scariose, with sparse glandular teeth, apex extremely acute; 1-nerved, stipular glands absent; petals yellow, brownish-red when dried, closely narrow or oblanceolate, 4.0–8.0 mm long, glabrous; stamens 2.0–4.0 mm long; anthers 0.6-1.0 mm long, yellow; staminodia minute, sometimes absent; styles connate at the base to fused to half their length, 1.4–2.4 mm long; stigmata capitate, yellow. Fruit widely ovoid, yellow, 2.4–3.3 × 2.3–2.6 mm, glabrous, pericarp thin, apex pointed, dehiscent into 10 segments, false septa partially developed, septa sparsely ciliate but conspicuous along the margin; seeds elliptical, light brown, 1.6–2.0 × 1.0– 1.2 mm. Distribution: —Endemic to Mexico, in Coahuila, Nuevo Leon, and Zacatecas (Fig. 2b). Habitat and ecology: —Cardonal shrublands, crassi-rosette-leaved thorny shrublands, oak forests, oak-pine forests, yucca shrublands, thornless or sub-thornless small-leaved shrubland, high or medium sub-evergreen tropical forests, low deciduous thorny tropical forest, sandy arid desert vegetation. Elevation 1400–2250 m. Phaeozem, Lithosol, Regosol, and Xerosol soil types. Phenology: —Flowering in March–September; fruiting in March–October. Note: — Linum flagellare is quite variable in terms of habit, flower size, presence of stipular glands, and style attachment. It is usually confused with L. rupestre, which is far more common and with which it shares a similar habit, but from which it can be differentiated by the absence of stipular glands in most leaves, much smaller styles connate at the base or attached to half or almost half its length. In addition, petals exhibit a brownish-red color when dried, a character that persists and is observed in herbarium specimens. Conservation status: —According to the IUCN (2019) B criterion, L. flagellare is VU (B2abc(iii)), with an EOO of 28,947.347 km 2 and AOO of 36 km 2. It is worth mentioning that according to an evaluation carried out by CONABIO (2021), its habitat is constantly threatened by anthropic activities. Specimens examined: — MEXICO. Coahuila: Parras, Sierra de Parras, 2000 m, 25°21’00”N, 102°12’00”W, 19 September 1993, G. Nesom et al. 7645 (MEXU!); Saltillo, Suroeste de la Sierra de Zapalinamé, 2013 m, 25°14’32”N, 101°04’13”W, 15 April 2015, J.A. Encina & J.M. Cárdenas V. 4429 (ANSM!); Saltillo, Slope near Las Barrancas, 3 May 1959, D.S. Correll & I.M. Johnston 21403 (CHAPA!, MEXU!); Saltillo, Sierra de Zapalinamé, 2245 m, 25°15’26”N, 101°03’19”W, 16 August 2014, J.A. Encina et al. 3903 (CIIDIR!); 1.5 miles SW of Las Delicias, 1615 m, 26°14’00”N, 102°49’00”W, 15 August 1973, J. Henrickson 12476 (MEXU!); 3 km al S de El Frayle, 1953 m, 25°00’47”N, 101°20’06”W, 1 October 2016, M.A. Ayala-Ramos et al. 60 (MEXU!); 30 km WSW of Villa Ocampo, 1600 m, 27°15’00”N, 102°41’00”W, 26 September 1986, J. Henrickson & L. Woodruff 20376 (MEXU!). Nuevo Leon: Bustamante, Bustamante Canyon, 496 m, 26°32’58.45”N, 100°33’18.68”W, 13 August 1988, T.F. Patterson 6591 (TEX!). Zacatecas: Concepción del Oro, km 199 de la carretera Zacatecas-Saltillo, 1850 m, 7 May 1977, J. García P. 316 (CHAPA!); 2.5 miles NNE of Estación Camacho, 1860 m, 24°47’00”N, 102°13’00”W, 25 September 1973, J. Henrickson 13520 (MEXU!); 5 km by road WSW of Caopas, 1940 m, 24°46’00”N, 102°12’40”W, 28 March 1973, M.C. Johnston et al. 10453 (MEXU!); 7.5 km by road WSW of Caopas on road to Camacho, 1890 m, 24°45’20”N, 102°13’30”W, 28 March 1973, M.C. Johnston et al. 10449 (MEXU!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on page 154, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Small, J. K. (1907 g) Cathartolinum flagellare. North American Flora 25: 78.","Rogers, C. M. (1964 b) Linum coahuilense. Rhodora 66: 279.","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)","CONABIO (2021) Indice de Impacto Humano en la Biodiversidad Terrestre. Comision Nacional para uso y conocimiento de la Biodiversidad. Available from: http: // geoportal. conabio. gob. mx / metadatos / doc / html / indihum 14 gw. html (accessed 1 December 2021)"]}

Linum modestum C.M. Rogers (1964c: 406). (Fig. 8). Type:— MEXICO. Nuevo Leon: Pablillo, south of Galeana, side of arroyo, 1900–2000 m, Pennell 16976 (holotype US!, isotype PH!). Description: — Herbs, perennial, 15–20 cm in height, glabrous, root thin; stems erect ascending, dark-purple, striate, branched from the base, glabrous. Leaves, basal ones entire, arranged in whorls of 4; distal ones glandular-dentate, alternate; 0.7–4.3 × 0.3–2.3 mm, lanceolate, sessile, apex acute, 1-nerved, glabrous, rough, stipular glands absent. Inflorescence a panicle with thin branches, ascending, pedicels 3.5–14.7 mm long; bracts 0.6–1.1 mm long, margin glandular-dentate, apex rounded, stipular glands absent; sepals persistent, lanceolate to ovate, (1.2)1.7–1.8 × 0.5–0.7 mm, margin glandular-dentate, apex mucronate to subacute, 1-nerved, stipular glands absent; petals yellow-green, oblanceolate, 3.0– 3.5 mm long, glabrous; stamens 2.0 mm long; anthers 0.4–0.6 mm long, light yellow; staminodia minute or absent; styles free, 1.6–1.7 mm long; stigmata capitate, light yellow. Fruit widely ovoid, yellow, (0.9)1.5–1.6 × 1.1–1.5(1.7) mm, glabrous, pericarp thin, apex acute, dehiscent into 10 segments; false septa incomplete, true septa sparsely ciliate; seeds ovate to elliptical, light brown, 0.8 × 0.5 mm. Distribution: —Endemic to Mexico, in Nuevo Leon (Fig. 5c). Habitat and ecology: —Cypress-juniper forest, crassi-rosette-leaved thorny shrublands, pine forests. Elevation 1200–2300 m. Phaeozem, Lithosol, Regosol, Solonchak, and Xerosol soil types. Phenology: —Flowering in March–September; fruiting in July–November. Note: —The dark-purple striate stems, branched inflorescence, minute leaves and floral parts, and acute fruit, together with the narrow strip of gypsum soils where it thrives, make it one of the most unique species of the genus Linum in Mexico. Conservation status: —According to IUCN Red List Categories and Criteria (IUCN 2019), L. modestum is EN (B1 + 2ab(iii)). Its EOO is 803.899 km 2 and AOO is 40 km 2. In addition, this species is not only an endemic to Mexico, but also presents a type of edaphic endemism (Nesom 1983), so its distribution is restricted to a small area of the state of Nuevo Leon. Moreover, mining operations and human settlements are recorded in its distribution range (Toledo 2005, Salinas-Rodríguez 2015, Gutiérrez-García & Ricker 2019), which may exert pressure on the viability of its populations. Specimens examined: — MEXICO. Nuevo Leon: Galeana, Santa Rita, 2120 m, 25 June 1981, Hinton et al. 18196 (ANSM!, CIIDIR!, ENCB!, IEB!); Galeana, Santa Rita, 2010 m, 14 May 1981, Hinton et al. 18240 (ANSM!, ENCB!); Galeana, SW of Laguna de Labradores, 2267 m, 17 October 2003, Hinton et al. 28034 (ANSM!); Galeana, Santa Rita, 2160 m, 12 January 1989, Hinton et al. 19293 (CIIDIR!); Galeana, 700 m al NW del Rancho de Los aguacates, 2250 m, 08 October 1976, L. Lezama de la R., s.n. (INEGI!); Galeana, 12.2 road miles E of San Roberto Jct. on road to Galeana, 2150 m, 24°40’00”N, 100°09’00”W, 16 September 1980, J. Henrickson & P. Bekey 18517 (MEXU!); Galeana, Just S of Cerro Potosí, 2100 m, 24°46’00”N, 100°13’00”W, 10 October 1982, J. Henrickson & W. Hess 19265 (MEXU!); Galeana, 3.2 mi S of Galeana, 24°47’00”N, 100°03’00”W, 10 October 1985, B.L. Turner et al. 15553 (XAL!); Rayones, Galeana-Rayones + 18 km, 1270 m, 27 February 1990, Hinton et al. 20155 (CHAP!, CHAPA!); Rayones, Lomas Blancas in San Pedro Carrizales, 1204 m, 12 September 2008, Hinton et al. 28708 (ANSM!); Rayones, Sierra Pelillos, Puerto Mesa de León, 2100 m, 25°00’00”N, 100°16’00”W, 7 June 1988, J.A. Villarreal et al. 4359 (ANSM!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 159-160, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Rogers, C. M. (1964 c) Linum modestum. Rhodora 66: 406.","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)","Nesom, G. L. (1983) New species of Calochortus (Liliaceae) and Linum (Linaceae) from northern Mexico. Madrono 30: 250 - 254.","Toledo, V. M. (2005) Repensar la conservacion:? Areas naturales protegidas o estrategia bioregional? Gaceta Ecologica 77: 67 - 83. Ulloa-Ulloa, C., Acevedo-Rodriguez, P., Beck, S., Belgrano, M. J., Bernal, R., Berry, P. E., Brako, L., Celis, M., Davidse, G., Forzza, R. C.,","Salinas-Rodriguez, M. M. (2015) Conocimiento, manejo y conservacion de la diversidad floristica de la Sierra Madre Oriental, Mexico. Universidad Autonoma de Nuevo Leon. Mexico. PhD Thesis, pp. 242.","Gutierrez-Garcia, G. & Ricker, M. (2019) Influencia del clima en el crecimiento radial en cuatro especies de coniferas en la Sierra de San Antonio Pena Nevada (Nuevo Leon, Mexico). Revista Mexicana de Biodiversidad 90: e 902676. http: // dx. doi. org / 10.22201 / ib. 20078706 e. 2019.90.2676"]}

Linum neomexicanum Greene (1881: 183). (Fig. 7d). Type:— UNITED STATES OF AMERICA. New Mexico: Pinos Altos Mountains, Greene s.n. (holotype ND!, isotypes GH!, KANU, MO!). Cathartolinum neomexicanum Small (1907l: 73). Description: — Herbs, annual, 15–60 cm in height, glabrous, sometimes glaucous, root thin; stems erect, ascending, branching from the base, glabrous. Leaves entire, basal opposite, distal alternate, elliptical-oblanceolate, 8.0–15.0 × 1.0–1.8(–2.5) mm, sessile, apex subacute to acuminate, 1-nerved, rough, glabrous, stipular glands absent. Inflorescence a cymose panicle, thin, pedicels almost parallel to the stem, 1.0–4.0(–7.5) mm long; bracts 1.5–4.8 mm long, margin entire, apex acute, stipular glands absent; sepals persistent, linear-lanceolate to lanceolate, 2.3–4.1(–5.0) × 1.1–1.5 mm, margin glandular-dentate, apex acute to acuminate; 1-nerved, nervation evident; glabrous, stipular glands absent; petals yellow, oblanceolate, 4.0–7.0 mm long, glabrous; stamens 3.0–5.0 mm long; anthers 0.8–1.3(–1.5) mm long, orange; staminodia absent; styles free, 1.5–3.0 mm long; stigmata capitate, yellow. Fruit triangular-ovoid to widely ovoid, yellow with purple hues in the upper part, 1.7–2.6(3.5) × (1.9–) 2.7–3.5 mm, glabrous, pericarp thick, apex apiculate, dehiscent into 10 segments, false septa partially developed, septa with ciliate margins; seeds elliptical-ovate, pale reddish-brown, 2.0–2.5 × 1.1–1.3 mm. Distribution: — United States of America; in Mexico, in Baja California, Chihuahua, and Sonora (Fig. 5b). Habitat and ecology: —Cypress-juniper forest, oak-pine forests, pine forests. Elevation 1700–2900 m. Phaeozem, Lithosol, Luvisol, Planosol, Regosol, and Vertisol soil types. Phenology: —Flowering and fruiting in March–November. Note: —It is easily distinguished by its thin inflorescence and pedicels parallel to the stem. Within its distribution range, it is the only species with yellow flowers and free styles. However, when reviewing herbarium specimens, several L. pringlei specimens with white flowers were misidentified as L. neomexicanum. Conservation status: —According to the IUCN Red List Categories and Criteria (2019), L. neomexicanum is Endangered (B2abc(iii)), as it has an AOO of 20 km 2 and ≤ 5 localities are known in the country. However, considering its EOO (159,584.708 km 2) and its distribution in the United States of America it probably can be considered as LC. Specimens examined: — MEXICO. Baja California: Sierra San Pedro Mártir, 2475 m, 31°02’00”N, 115°27’00”W, 21 July 1970, R. Moran 17895 (ENCB!); Sierra San Pedro Mártir, 2000 m, 31°04’00”N, 115°33’00”W, 15August 1967, R. Moran & R.F. Thorne 14121 (ENCB!). Chihuahua: Guachochi, Rejogochi cerro oeste de Valle, 10/September/2002, F. Wyndham 20 (CIIDIR!, MEXU!); Sierra Madre, 29 September 1887, C.G. Pringle 1201 (MEXU!). Sonora: Agua Prieta, Arroyo Cajón del Diablo, 1772 m, 31°17’19”N, 108°47’49”W, 29 September 2009, T.R. Van Devender et al. 1693 (MEXU!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 161-162, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Greene, E. L. (1881) Linum neomexicanum. Botanical Gazette 6: 183. https: // doi. org / 10.1086 / 325454","Small, J. K. (1907 l) Cathartolinum neomexicanum. North American Flora 25: 73."]}

Linum mexicanum Kunth (1823: 39). (Fig. 7b). Type:— MEXICO. Guanajuato, Santa Rosa, Humboldt & Bonpland s.n. (holotype P-Humb. (photo, F-035185, IEB!)). Mesynium mexicanum Rafinesque (1837: 33). Cathartolinum mexicanum Small (1907k: 79). Description: — Herbs, perennial, 50–120 cm in height, glabrous or almost glabrous, often with a voluminous root; stems erect, striate, branched to the middle part, sometimes from the base, glabrous. Leaves entire, often ciliate, basal leaves opposite or in whorls, distal leaves frequently alternate, often lanceolate or suboblong, varying from linearlanceolate to oval, 10.0–45.0 × 4.0–20.0 mm, sessile or subsessile, apex acute, 2 prominent lateral nerves near the base, coriaceous, glabrous, occasionally pubescent on the abaxial surface, stipular glands present at the base. Inflorescence a cymose panicle, pedicels 2.1–12.6(–15.0) mm long; bracts 1.9–4.6 mm long, margin entire, apex acute, stipular glands black at the base; sepals persistent, lanceolate to ovate, 2.0–3.5 × 1.2–2.0 mm, margin glandular-dentate, apex acute or cuspidate provided with hairs, 3-nerved, stipular glands absent; petals light yellow, obovate, 8.0–12.0 mm long, glabrous; stamens 5.0–8.0 mm long; anthers 0.7–1.0 mm long, light brown; staminodia present; styles fused up to half or near the apex, 4.0–7.0 mm long; stigmata capitate, light brown. Fruit ovoid to conical or subspherical, yellow with purple hues in the upper portion, 1.7–2.3 × 1.6–2.4(–3.0) mm, glabrous, pericarp thick, apex apiculate, dehiscent into 10 acute segments, septa ciliate; seeds elliptical to oblong, reddish-brown, 1.5 × 1.0 mm. Distribution: —Endemic to Mexico, in Chiapas, Mexico City, State of Mexico, Guerrero, Jalisco, Michoacan, Oaxaca, Puebla, and Queretaro (Fig. 5a). Habitat and ecology: —Oyamel fir forest, deciduous forest, crassi-rosette-leaved thorny shrublands, oak forests, pine-oak forests, thorny shrubland, thornless or sub-thornless small-leaved shrubland, palm-tree forests, pine forests, grasslands, low deciduous tropical forest, low thorny evergreen tropical forest, medium or low evergreen tropical forest. Elevation 2000–2700 m. Acrisol, Andosol, Cambisol, Phaeozem, Lithosol, Luvisol, Ranker, Regosol, Rendzina, Vertisol, and Xerosol soil types. Phenology: —Flowering in May–September; fruiting in July–November. Note: — Linum mexicanum is closely related to L. orizabae, with which it shares much of its natural distribution, thus leading to recurrent taxonomic identification issues; L. mexicanum can only be differentiated by the presence of fused styles to half or three-quarters of their length. Conservation status: —According to the criterion B established by the IUCN (2019), L. mexicanum can be considered as VU (B2b(iii)), with an AOO of 64 km 2, which is added to the deterioration of its habitat as a consequence of its proximity to large nuclei of human population and an important loss of vegetation cover (Rodríguez-Echeverry & Leiton 2021).Although its EOO is 225,655.320 km 2, its distribution is scattered. It is worth mentioning that Rzedowski & Calderón de Rzedowski (1992) indicated that this species is at risk of extinction. Specimens examined: — MEXICO. Chiapas: Oxchuc, Terracería hacia 20 de Noviembre, 2050 m, 16°45’20”N, 92°20’58”W, 23 August 1995, H. Mejía E. & A. Luna G. 679 (XAL!); San Andrés Larrainzar, Cloud Forest near the summit of Chuchil Ton, 2700 m, 3 August 1972, D.E. Breedlove 26756 (CHAPA!); San Cristóbal de las Casas, Cerro San Cristóbal, 2195 m, 15 October 1965, D.E. Breedlove & P.H. Raven 13309 (MEXU!); San Cristóbal de las Casas, Arroyo del Rancho Pellizzi, 20 July 1986, A. Méndez G. 9166 (UAMIZ!); Totolapa, 6-8 km west of Teopisca, 2150 m, 16 August 1972, D.E. Breedlove 27054 (CHAPA!); Zinacantán, Paraje Navenchauk, 2195 m, 30 July 1981, D.E. Breedlove 51847 (MEXU!); Zinacantán, Paraje Patosil, 2100 m, 16°45’15”N, 92°44’29”W, 26 September 1994, A. Chame & M. de J. Gutiérrez 471 (MEXU!). Mexico City: Álvaro Obregón, La Angostura, 2480 m, 19°19’43.4”N, 99°14’11.1”W, 1 September 1941, E. Lyonnet 3436 (MEXU!). State of Mexico: Temascalcingo, 1.53 km de San José de los Reyes, 2714 m, 19°59’13”N, 100°06’33”W, 27 August 2014, D. Álvarez et al. 13634 (MEXU!). Guerrrero: General Heliodoro Castillo, Verde Rico, 2.3 km al N, Camino a la Cienega, 2050 m, 17°43’39”N, 99°53’39”W, 5 October 1998, R. Cruz-Durán 3066 (MEXU!). Jalisco: Ciudad Guzmán, Campamento de Atenquique en camino al cerro de la Media Luna, 2124 m, 18 September 2016, A. Castro et al. 4167 (IBUG!); Tecalitlán, Rancho El Tigre, 2100 m, 12 August 1979, F. Gutiérrez L. 20 (IBUG!); Tecalitlán, 17 km al E de Llanitos, 16 August 1990, J. Villa C. & J. Chávez L. 842 (IEB!, SLPM!). Michoacan: Epitacio Huerta, Cerca de Polvillas, 2600 m, 2 August 1990, Rzedowski 49726 (XAL!); Hidalgo, Cañada de la Trampa, San Lucas Huarirapeo, 2720 m, 1 October 2004, X. Madrigal S. 244 (MEXU!); Morelia, Cerro La Máscara, 2300 m, 12 September 1991, C. Medina G. 2359 (IBUG!, XAL!). Oaxaca: Ixtlán de Juárez, Suroeste del río de la Y, 2100 m, 17°19’5.9”N, 96°26’31.9”W, 24 September 2003, S. Figueroa B. & F.Y. Guzmán R. 801 (CHAP!, UAMIZ!). Puebla: Cholula, Camino al Cerro El Campanario, 2580 m, 19°04’45”N, 98°31’00”W, 24 August 1987, T. Ubierna 299 (MEXU!). Queretaro: Pinal de Amoles, 3-4 km al NE de Pinal de Amoles, 2230 m, 24 September 1991, E. Carranza G. 3534 (IEB!); Amealco, 2 km de Laguna de Servín, 2650 m, 22 August 1991, H. Díaz-Barriga et al. 6902 (XAL!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on page 158, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Kunth, K. S. (1823) Linum mexicanum. Nova Genera et Species Plantarum 6: 39.","Rafinesque, C. S. (1837) Mesynium mexicanum. Flora Telluriana 3: 33. https: // doi. org / 10.5962 / bhl. title. 7751","Small, J. K. (1907 k) Cathartolinum lecheoides, Cathartolinum mexicanum, Cathartolinum orizabae. North American Flora 25: 79.","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)","Rodriguez-Echeverry, J. & Leiton, M. (2021) Perdida y fragmentacion de ecosistemas boscosos nativos y su influencia en la diversidad de habitats en el hotspot Andes tropicales. Revista Mexicana de Biodiversidad 92: e 923449. https: // doi. org / 10.22201 / ib. 20078706 e. 2021.92.3449","Rzedowski, J. & Calderon de Rzedowski, G. (1992) Linaceae. In: Rzedowki, J. & Calderon de Rzedowski, G. (Eds.) Flora del Bajio y de Regiones Adyacentes. Fasciculo 6: 1 - 22. [ISBN: 0188 - 5170]"]}

Linum orizabae Planchon (1848c: 482). (Fig. 9a). Type:— MEXICO. Veracruz: Orizaba, H. G. Galeotti 821 (holotype K!). Linum hypericifolium C. Presl (1831: 2). Linum lecheoides S.Watson (1882: 332). Type:— MEXICO. San Luis Potosi: in montibus San Miguelito, J.G. Schaffner 600 (isotypes GH!, MEXU!, NY). Cathartolinum lecheoides Small (1907k: 79). Cathartolinum orizabae Small (1907k: 79). Cathartolinum hypericifolium Small (1907j: 80). Description: — Herbs, perennial, 20–80(160) cm in height, essentially glabrous, usually with thick root; stems erect, ascending, striate, often unbranched to the inflorescence, glabrous or sparingly pilose. Leaves entire or slightly dentate, basal leaves opposite or arranged in whorls of 4, distal leaves alternate, linear-lanceolate to oblong-lanceolate, 5.0–45.0 × (1.2–)2.0–9.0 mm, longer and wider toward the mid portion of the stem, sessile or subsessile, apex acute-acuminate; 1-nerved, prominent central nerve on the abaxial surface; membranous, glabrous, stipular glands present at the base. Inflorescence a cymose panicle, pedicels 1.5–4(16.4) mm long, occasionally with sparse whitish hairs, bracts 1.2– 2.5(–4.0) mm long, hairs scattered adaxially, margin entire, apex acuminate, stipular glands present at the base; sepals persistent, ovate to obovate, 1.5–2.5(–4.0) × 1.0–2.0 mm; margin entire, rarely with few glandular teeth; apex acute to shortly acuminate, apiculate, occasionally ciliated, slightly scariose; 1-nerved, nerve evident, sparsely pilose along the nerve, frequently glabrous on both sides, stipular glands present; petals yellow, obovate or oblanceolate, 3.0–8.0 mm long, glabrous; stamens 2.0–4.0 mm long; anthers 0.2–0.5 mm long, yellow; staminodia minute or absent; styles free or connate at the base, 0.9–2.0(3.6) mm long; stigmata capitate, yellow. Fruit ovoid to conical, yellow with purple hues in the upper part, 1.8–2.2(4.0) × 0.9–2.5(–3.0) mm, glabrous, pericarp thick, apex apiculate, dehiscent into 10 segments, false septa partially developed, septa ciliated; seeds compressed, elliptical or oblong, brown, 1.0–1.5 × 0.7–1.0 mm. Distribution: —Endemic to Mexico, in Mexico City, State of Mexico, Guerrero, Hidalgo, Jalisco, Michoacan, Morelos, Oaxaca, Puebla, Queretaro, and Veracruz (Fig. 5c). Habitat and ecology: —Oyamel fir forest, deciduous forest, cypress-juniper forest, chaparral shrubland, crassirosette-leaved thorny shrubland, cropland, oak forest, oak-pine forest, thornless or sub-thornless small-leaved shrubland, grasslands, pine forests, medium or low evergreen tropical forest. Elevation 1300–3500 m. Soils of volcanic origin of Acrisol, Andosol, Cambisol, Phaeozem, Fluvisol, Lithosol, Luvisol, Ranker, Regosol, Rendzina, Solonchak, Vertisol, and Xerosol types. Phenology: —Flowering in June–December; fruiting in October–January. Note: — Linum orizabae can be easily confused with L. mexicanum, since in part both species are sympatric and share a great morphological similarity. The only character detected that allows differentiating between the two species is the styles free or connate at the base, slightly smaller in L. orizabae. Conservation status: — Linum orizabae registers an EOO of 89,115.419 km 2, and although it has an AOO of 280 km 2, a value necessary to be considered endangered, it does not meet the necessary subcriteria. Therefore, this species can be considered as LC (IUCN 2019, 2021). It is important mentioning the affinity of this species to the Trans-Mexican Volcanic Belt. Specimens examined: — MEXICO. Mexico City: Álvaro Obregón, Santa Rosa, 2700 m, 18 August 1977, A. Ventura A. 2992 (CHAP!, CHAPA!); Álvaro Obregón, Santa Rosa, 2700 m, 30 April 1977, A. Ventura A. 2722 (CHAPA!); Álvaro Obregón, Santa Rosa, 2500 m, 1 August 1982, A. Ventura A. 4000 (CHAPA!); Álvaro Obregón, San Bartolo, 2700 m, 28 July 1979, A. Ventura A. 3475 (IBUG!, MEXU!, XAL!); Milpa Alta, San Lorenzo, 2650 m, 23 October 1976, A. Ventura A. 2337 (CHAPA!, XAL!); Milpa Alta, San Pablo, 2750 m, 7 July 1976, A. Ventura A. 1753 (CHAP!); Milpa Alta, San Lorenzo, 2650 m, 5 October 1976, A. Ventura A. 2237 (CHAP!, CHAPA!); Milpa Alta, Tenantitla, 2850 m, 31 January 1976, A. Ventura A. 925 (CHAPA!); Milpa Alta, San Salvador, 2800 m, 11 December 1976, A. Ventura A. 2468 (CHAPA!); Milpa Alta, San Pablo, 2750 m, 7 July 1976, A. Ventura A. 1753 (CIIDIR!); Milpa Alta, a 300 m de LR al W del Volcán Ocotecatl, 3320 m, 19°05’07”N, 99°01’25”W, 11 Jul /2004, J.E. Rivera et al. 3853 (MEXU!); Tlalpan, Topilejo, 2600 m, 25 July 1976, A. Ventura A. 1891 (CHAPA!, CIIDIR!); Xochimilco, Cerro de Esquehuil, 2800 m, 20 November 1976, A. Ventura A. 2411 (CHAP!, CHAPA!, XAL!); Xochimilco, Cerro de Esquehuil, 2800 m, 30 June 1976, A. Ventura A. 1701 (CHAP!, CHAPA!, CIIDIR!); Xochimilco, Cerro de Esquehuil, 2800 m, 16 July 1977, A. Ventura A. 2990 (CHAPA!). State of Mexico: Amecameca, 1 Km al E de San Antonio, 2250 m, 30 September 1979, B. Osorio C. 221 (ANSM!); Amecameca, 1 km al E de San Antonio, 2500 m, 27 September1981, F.J. Díaz P. 42 (CHAP!, CIIDIR!, IBUG!); Chapa de Mota, Cerro de Las Ánimas, 3105 m, 19°47’11.8”N, 99°31’47.9”W, 22 August 2009, C. Trejo-Díaz 203 (MEXU!); Donato Guerra, Camino a Llano Grande, 2500 m, 19°21’18”N, 100°14’40”W, 26 December 2005, G. Cornejo T. et al. 1714 (MEXU!); Texcoco, Santa Catarina, 2600 m, 14 July 1982, E. Ventura V. 386 (CHAP!, CHAPA!, UAMIZ!, XAL!); Texcoco, San Miguel Tlaixpan, 2500 m, 7 May1983, E. Ventura V. 881 (CHAP!, CIIDIR!); Texcoco, Santa Catarina, 3500 m, 29 March 1983, E. Ventura A. 656 (INEGI!, XAL!); Tlalmanalco, Arroyo Tlalmanalco, 5 km al ESE de San Rafael, 2790 m, 11 April 1977, S.D. Koch 7761 (CHAPA!); Tlalmanalco, 1 km al NE de Sto. Tomás Atzingo, 2450 m, 5 November 1982, J. García P. 1710 (CHAPA!); Villa Nicolás Romero, Libertad, 2200 m, 10 September 1978, A. Ventura A. 3313 (CHAPA!, CIIDIR!); Villa Nicolás Romero, 7 km antes de Tlazala de Fabela, 2450 m, 28 August 1984, J. García et al. 1867 (CHAPA!). Guerrero: Metlatónoc, al S de Yoso Tise´e, 2800 m, 17°15’00”N, 98°19’00”W, 21 September 1988, A. de Ávila 427 (MEXU!). Hidalgo: Mineral del Chico, El Chico, 2819 m, 20°11’54.99”N, 98°43’9.3”W, 1 September 1930, E. Lyonnet 146 (MEXU!). Jalisco: San Gabriel, 4.5 km al N de Atequizayán, 2617 m, 27 November 2016, V. Quintero F. et al. 1449 (CHAPA!, IBUG!); Venustiano Carranza, 15 km al NO de la carretera Cd. Guzmán-Autlán, 2260 m, 23 July 1990, J. Villa C. et al. 827 (IBUG!); Zapotlán el grande, Camino al Cerro de la Media Luna, 2136 m, 18 September 2019, A. Castro et al. 4190 (IBUG!). Michoacan: Cherán, Ladera NE del Cerro San Marcos, 2600 m, 15 August 1987, M. Pérez R. 211 (CHAP!, IBUG!); Cherán, 3 km al S de Cherán, 2400 m, 13 August 1987, M. Pérez R. 172 (CIIDIR!, IBUG!); Coeneo, Cerro El Timbe estación de microondas, 2450 m, 11 December 1985, H. Díaz-Barriga 1848 (CHAP!, XAL!); Hidalgo, Ladera W del Cerro San Andrés, 3030 m, 19°48’25”N, 100°37’37”W, 18 October 2012, G. Aguilar-Gutiérrez et al. 981 (IEB!); Hidalgo, Ladera S del Cerro San Andrés, 3375 m, 19°47’13”N, 100°35’48”W, 5 November 2010, G. Aguilar-Gutiérrez & S. Zamudio R. 236 (IEB!); Huiramba, Tupátaro, 2300 m, 28 August 1986, J.M. Escobedo 1177 (ANSM!); Huiramba, Parte alta del Cerro La Taza, 3190 m, 22 August 1986, H. Díaz B. & S. Zamudio 2648 (CIIDIR!, IBUG!); Huiramba, Parte alta Cerro Las Nieves, 3350 m, 17 July 1992, H. Díaz B. & E. García L. 7020 (XAL!); Lagunillas, Cerro El Águila, 2590 m, 19°36’37”N, 101°22’40”W, 12 October 2008, G. Cornejo T. & G. Ibarra M. 3190 (IEB!); Lagunillas, Cerro El Águila, 2620 m, 16°36’31”N 101°22’18”W, 12 October 2008, G. Cornejo T. & G. Ibarra M. 3248 (IEB!); La Piedad, Cerro Grande de la Piedad, 2500 m, 30 August 1994, S. Zamudio et al. 9372 (XAL!); Ocampo, a 1.1 km al SO de Cieneguillas, 2634 m, 19°34’29.4”N, 100°18’43”W, 10 July 2015, D. Álvarez 15764 (MEXU!); Ocampo, El Salto aprox. 3 km al E de Ocampo, 2240 m, 1 October 1989, R. Torres C. 13263 (XAL!); Ocuilán, 2 km al N de Santa Mónica, 2370 m, 18°99’16”N, 99°26’08”W, 20 July 1990, L. Zizumbo A. 17 (INEGI!); Santa Clara del Cobre, Cerro del Burro, 3200 m, 26 May 1988, E. Pérez-Calix 54 (CIIDIR!, IBUG!, XAL!); Santa Clara del Cobre, San Gregorio, 2650 m, 3 September 1988, E. Pérez-Calix 195 (CIIDIR!, IBUG!, XAL!); Santa Clara del Cobre, Cerro del Burro, 3000 m, 26 May 1988, J.M. Escobedo 1414 (IBUG!); Tlalmanalco, 3 km al E de San Rafael, 2700 m, 19 September 1976, S.E. Cortés 454 (INEGI!); Tlalpujahua, Camino Cerro San Miguel el Alto a Calvario, 2920 m, 21 October 1987, S. Zamudio R. 5791 (IBUG!, IEB!, XAL!); Zinapécuaro, Presa Pízcuaro, 3050 m, 25 January 1990, J.M. Jasso 1782 (CHAP!, XAL!); Zinapécuaro, Campamento turístico Los Azufres, 2850 m, 27 July 1986, S. Zamudio 4200 (CHAP!, CHAPA!, CIIDIR!); Zinapécuaro, Ladera SW del Cerro San Andrés, 3200 m, 28 August 1987, S. Zamudio R. 5518 (CHAPA!, IEB!); Zinapécuaro, La Cañada a 1 km al E de El Rincón de Jeráhuaro, 2580 m, 15 August 1989, M.J. Jasso 1381 (CIIDIR!, IBUG!); Zinapécuaro, Presa La Gachupina lado SW, 2910 m, 19 September 1989, M.J. Jasso 1598 (CIIDIR!, IBUG!); Zinapécuaro, Laguna de Los Azufres, 2870 m, 30 August 1986, H. Díaz B. & S. Zamudio 2701 (IBUG!); Zitácuaro, Camino al Cerro Cacique, 2230 m, 16 September 1989, R. Torres & M. Ramírez 13003 (XAL!). Morelos: Huitzilac, Zempoala, 19 September 1938, E. Lyonnet 2485 (XAL!). Oaxaca: Ixtlán de Juárez, Northwest slope of Cerro Humo Chico, 2870 m, 17°29’17.12”N, 96°29’51.5”W, 9 November 1983, D.E. Breedlove & F. Almeda 59969 (MEXU!). Puebla: Cholula, Camino a Tepetzingo, 19°04’45”N, 98°31’30”W, 2650 m, 4 November 1987, M. Tlapa A. & G. Ubierna 1275 (XAL!). Queretaro: Amealco, 8 km al NE de San Pablo, 2700 m, 23 October 1989, Rzedowski 49177 (IEB!). Veracruz: Acajete, Entre Acajete y Puentecillas, 1950 m, 27 June 1985, M. Chazaro B. & M. Leach 3405 (XAL!); Acajete, Masatepec, 950 m, 14 May 1975, F. Ventura A. 11336 (XAL!); Acajete, Acajete, 1950 m, 14 May 1979, F. Ventura A. 16079 (XAL!); Acajete, La Joya, 2050 m, 11 July 1980, F. Ventura A. 17484 (XAL!); Acultzingo, Cumbres de Acultzingo, 2250 m, 18°43’10”N, 97°17’49”W, 5 November 1985, J.L. Martínez & R. Acosta P. 916 (XAL!); Calcahualco, A 2 km de Ahuihuixtla, camino a Tres Aguas (Coscomatepec), 1750 m, 19°08’00”N, 97°03’00”W, 25 May 1985, J.L. Martínez & F. Vázquez 271 (IBUG!); Calcahualco, San Miguel Tlacotiopa, 2600 m, 19°06’00”N, 97°14’00”W, 30 July 1985, J.L. Martínez & F. Vázquez 527 (IBUG!, XAL!); Calcahualco, El Raicero, 3151 m, 19°06’17”N, 97°13’53”W, 12 August 2009, D. Jímeno S. 1146 (XAL!); Calcahualco, A 10 km al O de Escola, 2100 m, 19°09’00”N, 97°13’00”W, 26 June 1985, J.L. Martínez & F. Vázquez 339 (XAL!); Chiconquiaco, entre Chiconquiaco y Planta del Pie, 2100 m, 11 July 1984, M. Chazaro & L. Robles 3107 (IBUG!, XAL!); Coscomatepec, 8 km SW of Escola, 2500 m, 19°07’00”N, 97°11’00”W, 8 July 1982, M. Nee & G. Diggs 24859 (XAL!); Las Minas, Vereda de Cruz Blanca Rinconada, 2250 m, C. Duran E. y P. Burgos 496 (XAL!); Las Minas, Cerro La Tolva, 19°39’00”N, 97°08’00”W, 22 July 1989, C. Duran E. & M. Bielma 945 (XAL!); Las Minas, Vereda de Cruz Blanca a Las Minas, 19°40’00”N, 97°10’00”W, 17 July 1993, C. Duran E. & L. Leal 1141 (XAL!); Orizaba, Ladera NW del cerro del “Borrego”, 1350 m, 28 January 1984, J. García P. 1783 (CHAPA!); Rafael Ramírez, Rancho Casa Blanca, carretera a Perote, 2300 m, 19°39’00”N, 97°07’00”W, 27 September 1983, F. Vázquez B. 1280 (XAL!); Tonayan, Arriba de Monte Real, 2100 m, 1 September 1982, M. Cházaro & J. Márquez 2612 (CHAPA!); Tonayan, Arriba de Monte Real rumbo a La Magdalena, 2050 m, 1 June 1981, M. Cházaro B. 1559 (IBUG!, XAL!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 162-163, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Planchon, J. (1848 c) Linum orizabae. London Journal of Botany 7: 482.","Presl, C. B. (1831) Linum hypericifolium. Reliquiae Haenkeanae 2: 2.","Small, J. K. (1907 k) Cathartolinum lecheoides, Cathartolinum mexicanum, Cathartolinum orizabae. North American Flora 25: 79.","Small, J. K. (1907 j) Cathartolinum hypericifolium, Cathartolinum puberulum, Cathartolinum vernale. North American Flora 25: 80.","IUCN (2019) Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Subcommittee. Downloadable from: https: // www. iucnredlist. org / resources / redlistguidelines (accessed 22 April 2022)","IUCN (2021) The IUCN Red List of Threatened Species. Version 2019 - 3. IUCN Red List Unit, Cambridge U. K. Available from: https: // www. iucnredlist. org (accessed 15 October 2021)."]}

Linum rupestre Engelmann (1850: 232). (Fig. 9d). Type:— UNITED STATES OF AMERICA. Texas: New Braunfels, Lindheimer 337 (holotype GH!, isotypes MO!, NY!, PH!, UC, US!, YU!). Linum rupestre var. cymosulum Engelmann (1852a: 26). Type:— MEXICO. Coahuila: Buena Vista, J. Gregg 63; 1847 (Holotype: MO!) Cathartolinum rupestre Small (1907d: 76). Cathartolinum wrightii Small (1907d: 76). Type:— UNITED STATES OF AMERICA. Texas: from western Texas to El Paso, C. Wright 71 (holotype NY!, isotypes GH!, UC, US!) Linum wrightii H.J.P. Winkler (1931: 116). Description: — Herbs, perennial, 25–50(75) cm in height, glabrous, sometimes sparsely pubescent in the basal portion, root thin; stems erect, thickened, striate, unbranched up to the level of the inflorescence, essentially glabrous. Leaves entire, sometimes slightly dentate; basal leaves alternate or opposite, distal leaves alternate; linear to linear-lanceolate, 4.0–26.0 × (0.3) 0.5–2 mm, sessile; apex acute to acuminate, whitish; 1-nerved, coriaceus, glabrous, stipular glands present at the base. Inflorescence a cymose panicle, pedicels 2.4–21.0 mm long; bracts 2.2–5.5 mm long, margin glandular-dentate; apex acuminate, whitish; stipular glands at the base, conspicuous, black; sepals persistent, lanceolate to ovate, (2.4)2.5–5.0 × 0.8–1.2(1.5) mm, generally with a dark wine-red color; margin glandular-dentate, occasionally scariose; apex acuminate to cuspidate, whitish tip, 1-3-nerved, conspicuous nerves, glabrous, stipular glands present at the base; petals yellow, oblanceolate or obcordate, 6–11 mm long, pubescent near the base; stamens 2.0–8.0 mm long; anthers 0.5–1 mm long, yellow; staminodia present, minute; styles free, 3.0– 6.5 mm long; stigmata capitate, yellow. Fruit widely ovoid, yellow, 1.8–2.4 × (1.0)2.0–3.0 mm, glabrous, pericarp thin, apex acute, dehiscent into 10 segments, false septa partially developed, septa with marginal cilia; seeds ovate to widely oblong, reddish-brown, 1.2–1.6 × 1.0 mm. Distribution: — United States of America; in Mexico, in Aguascalientes, Chiapas, Chihuahua, Coahuila, Durango, Guanajuato, Nuevo Leon, Oaxaca, Puebla, Queretaro, San Luis Potosi, Tamaulipas, Zacatecas, and Veracruz (Fig. 2a). Habitat and ecology: —Deciduous forest, cypress-juniper forest, cardonal shrublands, chaparral shrubland, crassirosette-leaved thorny shrublands, oak forests, oak-pine forests, yucca shrublands, thorny shrubland, thornless or subthornless small-leaved shrubland, prickly-pear cacti shrublands, palm-tree forests, grasslands, low deciduous tropical forest, low deciduous thorny tropical forest, sandy arid desert vegetation, zacatonal alpine grasslands. Elevation 1200– 3000 m. Limestone Andosol, Cambisol, Kastanozem, Phaeozem, Lithosol, Luvisol, Regosol, Rendzina, Solonchak Vertisol, Xerosol, and Yermosol soil types. Phenology:—Flowering and fruiting in September–December. Note: —Its narrow leaves and absence of foliar whorls are traits that allow differentiating L. rupestre from its closest related species. The morphology resembles L. scabrellum, with which it is usually confused; however, L. rupestre is glabrous. It also resembles L. flagellare in habit, but the presence of stipular glands in leaves and sepals, as well as the free and much longer styles in L. rupestre, allow differentiating it from the latter. Conservation status: — Linum rupestre is one of the most widely distributed Linum species in Mexico, with a recorded EOO of 596,195,131 km 2 and AOO of 220 km 2. This, together with its presence in various environments in the country, means that it can be considered as LC. Specimens examined: — MEXICO. Aguascalientes: Tepezalá, 4 km al E de Tepezalá, 2000 m, 11 September 1980, M. De la Cerda & G. García 276 (CIIDIR!); Tepezalá, 2 km al E de Tepezalá, 2200 m, 22°13’28”N, 102°08’14”W, 29 May 2009, G. García 5581 (CIIDIR!); Tepezalá, Arroyo Las Pilas, 2024 m, 22°15’59”N, 102°10’30”W, J. Martínez-Ramírez 2570 (INEGI!); Tepezalá, 500 m al NE de la cementera Cruz Azul, 2034 m, 22°11’27.66”N, 102°11’53.98”W, 1 February 2013, J. Martínez R. 2295 (INEGI!); Tepezalá, 4 km al E de Tepezalá, 2247 m, 22°13’13.1”N, 102°08’6.1”W, 19 April 2013, Araiza-Arvilla 346 (INEGI!). Chiapas: Oxchuc, Tolbil Ja´, 3000 m, 16°49’51”N, 92°15’50”W, 20 June 1988, F. Goméz-Santiz 244 (XAL!). Chihuahua: Chihuahua, 2.0 mi NE of Aquiles Serdán, Sierra Santa Eulalia, 1530 m, 28°30’00”N, 105°52’0.01”W, 19 July 1977, E. Lehto 21539 (ASU!). Coahuila: Arteaga, Sierra de Zapalinamé, 1928 m, 25°24’51”N, 100°50’10”W, 15 July 2015, J.A. Encina & J.M. Cárdenas V. 4913 (ANSM!, MEXU!); Candela, Sierra de Pájaros Azules Campo Santa María, 1800 m, 27°01’00”N, 100°50’00”W, 11 January 1997, M.A. Carranza et al. 2730 (ANSM!, XAL!); Castaños, Sierra La Gavia Rancho La Gavia, 1295 m, 26°10’00”N, 101°18’30”W, 10 August 1995, M.A. Carranza & J. Encinas 2263 (CHAP!, CIIDIR!, XAL!); Cuatrociénegas, Rancho Potrero Menchaca, 1300 m, 1 May 1981, L.E. Rodríguez G. 154 (ANSM!); General Cepeda, Sierra de la Paila, 1750 m, 25°38’00”N, 101°35’00”W, 24 May 1990, J.A. Villarreal et al. 5640 (ANSM!, CHAPA!); General Cepeda, Sierra de la Paila, parte Oeste, 1560 m, 26°05’00”N, 101°44’00”W, 18 April 1992, J.A. Villarreal et al. 6349 (ANSM!); General Cepeda, Sierra de la Paila valle de La Nopalera, 1750 m, 25°38’00”N, 101°35’00”W, 27 April 1990, J.A. Villarreal et al. 5620 (ANSM!); Monclova, On Route 30, west of Monclova, 22 December 1977, N.A. Harriman 14218 (CHAPA!); North flank of Sierra de los Alamitos, 1400 m, 26°30’00”N, 102°21’00”W, 14 June 1972, F. Chiang et al. 7772 (MEXU!); Ocampo, Sierra la Encantada, Rcho. Puerto del Aire, 1250 m, 28°17’00”N, 102°28’00”W, 8 September 1990, M.A. Carranza et al. 743 (ANSM!); Parras, Arroyo seco en el Rancho El Tunal, 2020 m, 25°21’00”N, 101°59’30”W, 16 April 1981, A. Rodríguez & M.A. Carranza 205 (ANSM!); Parras, Rancho El Tunal, 2050 m, 25°20’00”N, 101°55’00”W, 7 October 1983, A. Rodríguez & M. Carranza 917 (ANSM!, CIIDIR!); Parras, Sierra de Parras en el arroyo seco del Rancho El Tunal, 2050 m, 1 September 1981, A. Rodríguez & P. Antonio H. 564 (ANSM!); Parras, Arroyo seco en el Rancho El Tunal, 2050 m, 25°21’00”N, 101°59’30”W, 16 April 1981, A. Rodríguez & M.A. Carranza s.n. (CIIDIR!); Ramos Arizpe, El Cedral Sierra de la Paila, 1600 m, 26°02’00”N, 101°23’00”W, 16 October 1986, J.A. Villarreal et al. 3551 (ANSM!); Ramos Arizpe, Sierra de la Paila Ejido el Cedral, 1900 m, 25°57’00”N, 101°33’00”W, 4 October 1989, J.A. Villarreal et al. 5249 (ANSM!); Ramos Arizpe, Cañada el Diente Sierra de la Paila, 1600 m, 26°09’00”N, 101°30’00”W, 5 October 1988, J.A. Villarreal & M.A. Carranza 4696 (ANSM!); Ramos Arizpe, Cañada el Diente Sierra de la Paila, 1600 m, 26°09’00”N, 101°30’00”W, 19 September 1989, J.A. Villarreal & M.A. Carranza 5217 (ANSM!); Ramos Arizpe, El Cedral Sierra de la Paila, 1600 m, 26°02’00”N, 101°23’00”W, 20 August 1987, J.A. Villarreal & M.A. Carranza 3928 (IBUG!, MEXU!); Saltillo, Entrada Cañón de San Lorenzo, 1974 m, 25°20’22”N, 100°59’10”W, 26 April 2015, J.A. Encina & J.M. Cárdenas V. 4654 (ANSM!); Saltillo, Ladera baja de la Sierra de Zapalinamé, 2051 m, 25°19’47”N, 101°00’47”W, 25 August 2007, J.A. Encina et al. 1905 (ANSM!); Saltillo, El Chiflón, aprox. 35 km al NW de Saltillo, 1400 m, 25°27’36”N, 101°19’07”W, 28 July 1998, M.A. Carranza & J. Valdés R. 2958 (ANSM!); Saltillo, Rancho Los Ángeles, 1900 m, 28 July 1982, G. Villaseñor et al. 1633 (ANSM!); Saltillo, Estación de Microondas Vega, 1600 m, 25°26’00”N, 101°06’00”W, 5 June 1992, J.A. Villarreal et al. 6625 (ANSM!); Saltillo, Rancho “Dos arbolitos”, 1800 m, 15 June 1981, M.A. Carranza et al. s.n. (ANSM!); Saltillo, Oeste de la Sierra de Zapalinamé, 1951 m, 25°20’7.19”N, 101°01’2.03”W, 19 April 2015, J.A. Encina et al. 4482 (ANSM!); Saltillo, Camino del Cuatro Sierra de Zapalinamé, 2330 m, 25°21’35”N, 100°56’08”W, 26 July 2003, J.A. Encina et al. 1139 (ANSM!); Saltillo, S de Saltillo camino a Zacatecas, 1 km al N de La Minita, 2015 m, 25°09’28.6”N, 101°05’52”W, 1 October 2016, M.A. Ayala-Ramos et al. 57 (MEXU!). Durango: El Mezquital, 5 km al NW de Yonora, 2020 m, 23 May 1987, M. González & S. Acevedo 2214 (ANSM!, CIIDIR!, IEB!); El Mezquital, 48 km de Durango, 21 April 1981, Y. Herrera 43 (CIIDIR!); Nombre de Dios, 3 km al W de La Parrilla, 14 November 1983, S. González et al. 2800 (CHAP!, CHAPA!, CIIDIR!, IBUG!). Guanajuato: Comonfort, 2 k al NE de Empalme Escobedo, 1900 m, 27 June 1987, Rzedowski 43440 (CIIDIR!, IBUG!, XAL!); San Miguel de Allende, Atotonilco, 1900 m, 8 October 1992, Rzedowski 51740 (XAL!); San Miguel de Allende, 17 km al NW de San Miguel de Allende, 1900 m, 23 August 1988, Rzedowski 47143 (XAL!); Xichú, Llano Grande 10 km al Este de Xichú, 1500 m, 14 September 1989, E. Ventura & E. López 7322 (XAL!). Nuevo Leon: Aramberri, near to San Francisco, 1750 m, 01 June 1997, Hinton et al. 27060 (ANSM!); Aramberri, km. 5 Carretera La Escondida-Aramberri, 1400 m, 24°06’19”N, 99°53’55”W, 26 August 2005, P. Carrillo-Reyes & V. Sosa, 4654 (IBUG!); Cadereyta, Ca. 4 km al NE de Cadereyta Jiménez, 20 April 1973, J. Marroquín 2518 (ANSM!); Dr. Arroyo, Santa Gertrudis, nr., 1780 m, 16 March 1993, Hinton et al. 22708 (ANSM!); Galeana, Cerro El Potosí, SE of., 2210 m, 23 July 1983, Hinton et al. 18526 (ANSM!, CHAPA!, CIIDIR!, IBUG!, XAL!); Dr. Arroyo, Matehuala-Dr. Arroyo aprox. 38 km, 17 June 1992, J.A. Villarreal & M.A. Carranza 6554 (ANSM!); Galeana, El Barrial, 1620 m, 24 September 1979, Hinton et al. 17662 (IEB!); Zaragoza, Zaragoza, nr., 1365 m, 28 July 1993, Hinton et al. 23115 (ANSM!); Zaragoza, Sierra El Soldado, 2850 m, 24°48’00”N, 99°52’00”W, 24 August 1989, J.A. Villarreal et al. 4920 (ANSM!). Oaxaca: Cuicatlán, 16 km al W por la terracería que va rumbo a San Pedro Jocotipac, 1750 m, 19 August 1987, A. Salinas T. 4323 (IEB!); San Pedro Jocotipac, Loma de En medio 5 km al SE de San Pedro Nodon, 1910 m, 24 October 1991, P. Tenorio L. & E. Martínez 17903 (MEXU!). Puebla: Chapulco, 2 km antes de llegar a Nicolas Bravo, 2300 m, 28 September 1989, M. Chazaro B. et al. 6094 (XAL!). Queretaro: Jalpan de Serra, Cerro de los Fresnos, 1500 m, 4 September 1989, C. Guzmán 107 (IEB!). San Luis Potosi: Catorce, San Antonio, 2146 m, 23°31’34.75”N, 100°56’16.35”W, 13 October 2016, J. López H. 77 (INEGI!); Charcas, Camino Charcas-Villa de Cos, 2215 m, 23°09’49.6”N, 101°10’54.9”W, 13 September 2020, A. Villalvazo-Hernández & J. González-Velasco 54 (CHAPA!); Charcas, Sierra de Monte Grande, 2175 m, 14 September 1989, J.A. Reyes A. 460 (CHAP!, CHAPA!, IBUG!); Charcas, Sierra de Monte Grande, 2175 m, 26 October 1989, J.A. Reyes A. 923 (CHAPA!, IEB!, SLPM!); Charcas, Sierra de Monte Grande, 2500 m, 13 September 1989, J.A. Reyes A. 392 (CHAPA!); Charcas, Sierra de Monte Grande, 2175 m, 23 October 1989, J.A. Reyes A. 875 (CHAPA!); Charcas, Sierra de Monte Grande, 2300 m, 14 September 1989, J.A. Reyes A. 427 (CHAPA!); Moctezuma, “La Calera” 2.5 km al Oeste del Estanco, 1980 m, 20/August/1976, M. Bustos Z. s.n. (CHAPA!). Tamaulipas: Víctoria, ca 17 mi by rd SW of Cd. Víctoria, 1086 m, 23°36’00”N, 99°12’00”W, 31 July 1976, G.L. Webster & W.S. Armbruster 20567 (TEX!). Veracruz: Totalco, 4 km al SW de Alchichica, 235 m, 19 May 1975, M. Vázquez-Torres et al. 1968 (CIB!); Perote, Perote, 19°19.3’00”N, 97°13’35.79”W, 2494 m, 19 December 1998, G. Castillo-Campos 19099 (XAL!). Zacatecas: Jerez, A 2 km al Noreste de la comunidad de Puerta de Chula, 2130 m, 22°42’8.13”N, 102°52’54.81”W, 15 October 2020, L. Hurtado-Reveles 674 (CHAPA!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 166-167, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Engelmann, G. (1850) Linum rupestre. Boston Journal of Natural History 6: 232.","Engelmann, G. (1852 a) Linum greggii, Linum rupestre var. cymolosum. Smithsonian Contributions to Knowledge 3: 26.","Small, J. K. (1907 d) Cathartolinum coulterianum, Cathartolinum rupestre, Cathartolinum schiedeanum, Cathartolinum wrightii. North American Flora 25: 76."]}

Linum pringlei S.Watson (1888: 269). (Fig. 9b). Type:— MEXICO. Chihuahua: shaded slopes, Sierra Madre, Pringle 1200 (holotype US!, isotypes GH!, MSC, NY!). Cathartolinum pringlei Small (1907c: 74). Description:— Herbs, perennial, 23–68 cm in height, glabrous, root thin; stems erect, branched from near the base, rigid ascending branches, extended, glabrous. Leaves, basal entire, opposite; distal discretely dentate, alternate; lanceolate or oblanceolate, 8.0.0–19 × 0.7–3.5 mm, sessile, apex acute or rounded, 2-nerved, membranous, glabrous, stipular glands absent. Inflorescence a cymose panicle, pedicels 3.0–14.0 mm long; bracts 1.7–3.4 mm long, margin sparsely dentate, apex acute, stipular glands absent; sepals persistent, ovate to lanceolate, 3.0–4.5 × 0.8–2.1 mm, margin entire or sparsely dentate above the mid portion to glandular-dentate, apex acute to acuminate, 1-nerved, glabrous, stipular glands absent; petals white to pinkish, oblanceolate, 5.0 – 8.0 mm long, glabrous; stamens 2.0–3.0 mm long; anthers 0.6–0.8 mm long, light yellow; staminodia present; styles free, 1.1–2.0 mm long; stigmata capitate, white. Fruit ovoidpyriform, yellow with purple hues in the upper part, 2.3–2.7 × 2.3–2.8 mm, glabrous, pericarp thin, apex acuminate, dehiscent into 10 segments, false septa partially developed, septa ciliated along the margins; seeds narrow to widely ovate, reddish-brown, 1.5–1.8 × 0.8–1.1 mm. Distribution: —Endemic to Mexico, in Aguascalientes, Chihuahua, Coahuila, Durango, and Jalisco (Fig. 5c). Habitat and ecology: —Oyamel fir forest, cypress-juniper forest, oak forests, oak-pine forests, thornless or small-leaved sub-thornless shrubland, palm-tree forests, pine forests. Elevation 1900–2900 m. Cambisol, Kastanozem, Phaeozem, Lithosol, Luvisol, Regosol, Rendzina, Vertisol, and Xerosol soil types. Phenology: —Flowering in March–September; fruiting in June–October. Note: —It is easily distinguished from other Mexican flax species by the white to pinkish color of the corolla; however, it is often confused with L. neomexicanum based on vegetative traits. The ovoid-pyriform fruits of L. pringlei are another character that can be used to identify the species. Conservation status: — Linum pringlei registers an EOO of 229,843.785 km 2, and an AOO of 120 km 2. In addition, the species is known from> 10 localities therefore it is considered as LC. However, the species, besides being endemic, presents a not continuous distribution that affects the estimation of EOO. Furthermore, template forests of the high regions of Mexico as the north-western portion—the area of distribution of the species—are disappearing due to the development of agriculture and livestock (Gutiérrez-Garcia & Ricker 2019, CONABIO 2021), so L. pringlei could be threatened in the short term. Specimens examined: — MEXICO. Aguascalientes: San José de Gracia, 10 km al NW de la Congoja, 2630 m, 22°12’39.2”N, 102°38’5.9”W, 16 October 2013, Murillo-Pérez 525 (INEGI!); San José de Gracia, 12 km al SW de la Congoja, 2700 m, 16 October 1973, Rzedowski & McVaugh 778 (MEXU!). Chihuahua: Ocampo, Parque Nacional, Cascada de Basaseachi, 2100 m, 28°11’00”N, 108°12’30”W, 3 October 1986, R Spellenberg et al. 8674 (CIIDIR!). Coahuila: Saltillo, Ladera caliza 3 km al S de El Frayle, 1953 m, 25°00’47.6”N, 101°20’6.8”W, 1 October 2016, M.A. Ayala-Ramos et al. 60 (MEXU!). Durango: Cuencamé, Cuencamé de Ceniceros, 12 October 1973, J. Marroquín 2648 (ANSM!); Durango, Predio Las Bayas, 2710 m, 8 August 1990, A. García & M. González 569 (CHAPA!, CIIDIR!); Durango, Parque El Tecuán, 4 September 1984, F. Casillas et al. 38 (CIIDIR!); Durango, Parque El Tecuán, 30 August 1984, F. Casillas et al. 40 (CHAPA!, IBUG!); Durango, Predio Las Bayas, 2700 m, 23°25’00”N, 104°51’00”W, 8 August 1990, A. García & M. González 605 (CIIDIR!); Durango, Parque El Tecuán, 30 August 1984, F. Casillas et al. 40 (CIIDIR!); Durango, Parque El Tecuán, 4 September 1984, F. Casillas et al. 39 (CIIDIR!); Durango, Parque El Tecuán, 4 September 1984, F. Casillas et al. 46 (CIIDIR!); El Mezquital, 19 km de Los Charcos, 2400 m, 4 October 1983, S. González & M. González 2560 (ANSM!, CHAP!, CHAPA!, CIIDIR!, IBUG!, MEXU!); El Mezquital, 22 km al NE de Los Charcos, 2750 m, 1 November 1982, S. González & J. Rzedowski 2345 (CHAPA!, CIIDIR!); El Mezquital, Rancho de La Mesa, 28 September 1985, I. Solís 391 (CIIDIR!, IEB!, MEXU!); Otaez, Entre Llano Blanco y San José de la Escalera, 5 October 1990, A. Benítez 2654 (CHAP!, CIIDIR!, MEXU!); Puente El Cajón San Antonio a 10 km de Altares, 1510 m, 2 October 1990, O. Bravo B. 1711 (CHAP!, CIIDIR!); Súchil, Trampa Las Iglesias a 2 km de Alemán, 19 September 1986, F. Acevedo 245 (ANSM!, CHAP!, CIIDIR!); Súchil, Potrero Tinajíta, ejido San Juan de Michis, 23 September 1985, J. Alvarado 60 (ANSM!, CHAPA!, CIIDIR!, IBUG!, IEB!); Súchil, 4 km al SW de Piedra Herrada, 2400 m, 11 September 1981, S. González 1948 (ANSM!, CHAPA!, CIIDIR!, ENCB!, IEB!, XAL!); Súchil, Arroyo El Ranchero, 2400 m, 23°22’03”N, 104°18’03”W, 12 August 1990, S. González & M. González 4751 (CIIDIR!, IBUG!); Súchil, Reserva de la Biosfera de La Michilia, 23°23’99”N, 104°14’99”W, 1 October 1983, G. Flores 13519 (CIIDIR!); Súchil, Arroyo Las Iglesias, 12 September 1986, F. Acevedo 234 (CIIDIR!); Súchil, Mesa EL Burro, 2700 m, 23°23’99”N, 104°17’99”W, 18 September 1985, S. González 3235 (CHAP!, CHAPA!; CIIDIR!, UAMIZ!); Súchil, Arroyo Los Indios, 19 September 1985, J. Alvarado 36 (CIIDIR!); Tepehuanes, 50 km de Tepehuanes, 2570 m, 12 September 1989, O. Bravo B. 316 (CHAP!, CIIDIR!); Tepehuanes, 5 km de la Mesa Alta, 2450 m, 6 September 1989, O. Bravo B. 244 (CHAP!, CIIDIR!); 4 km al NW of Los Angeles along road between Mazatlan and Durango, 2500 m, 28 October 1973, D.E. Breedlove 35739 (MEXU!). Jalisco: Tequila, Cima del Cerro (Volcán) de Tequila, 2850 m, 8 October 1988, M. Cházaro B. et al. 5723 (IBUG!, IEB!); Mezquitic, 5 km al NE de El Mortero por el camino a Monte Escobedo, 2300 m, 22°22’00”N, 103°37’00”W, 22 September 2001, P. Carrillo-Reyes & E.M. Guevara 2677 (IBUG!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on page 165, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Small, J. K. (1907 c) Cathartolinum catharticum. Cathartolinum pringlei. Cathartolinum scabrellum. North American Flora 25: 74.","Gutierrez-Garcia, G. & Ricker, M. (2019) Influencia del clima en el crecimiento radial en cuatro especies de coniferas en la Sierra de San Antonio Pena Nevada (Nuevo Leon, Mexico). Revista Mexicana de Biodiversidad 90: e 902676. http: // dx. doi. org / 10.22201 / ib. 20078706 e. 2019.90.2676","CONABIO (2021) Indice de Impacto Humano en la Biodiversidad Terrestre. Comision Nacional para uso y conocimiento de la Biodiversidad. Available from: http: // geoportal. conabio. gob. mx / metadatos / doc / html / indihum 14 gw. html (accessed 1 December 2021)"]}

Linum usitatissimum Linnaeus (1753: 277). (Fig. 10d). Type:—Habitat hodie inter segetes, Europae australis. Herb. Clifford 114, Linum no. 1. (lectotype BM!). Linum angustifolium Hudson (1778: 134). Linum humile Miller (1768: 2). Description:— Herbs, annual, 20–100 cm in height, glabrous, root thick; stems erect, smooth to simple striate, sometimes sparsely branched from the base, cylindrical, glabrous. Leaves entire, alternate, linear to linear-lanceolate, 10.0–40.0 × 0.7–3.0(4.0) mm, sessile, apex acute to acuminate, 1-nerved, scariose, glabrous, stipular glands absent. Inflorescence an open cymose panicle, glabrous; pedicels glabrous, 20-35 mm long; bracts 10.0–24.0 mm long, glabrous, margin entire, apex acute, stipular glands absent; sepals persistent, elliptical to ovate, 5–8 mm long, margin entire, thoroughly ciliated toward the apex or finely ciliate-fimbriate, scariose, apex acuminate, 1-nerved, stipular glands absent; petals blue, obovate, 9–15 mm long, glabrous; stamens 4.0–5.0(7.0) mm long; anthers (1.0)1.8–2.0 mm long, bright-yellow; staminodia absent; styles free or connate at the base, 3.0–6.0 mm long; stigmata linear or claviform, white. Fruit widely ovate to subglobose, yellow, 6–10 × 5–10 mm, glabrous, pericarp thick, apex rounded, dehiscent into 10 segments; false septa ciliated; seeds lanceolate, brown, 4.0–6.0 × 2.5–3.0 mm. Distribution: —Native of Europe and Asia (India, Eastern Mediterranean and Near East). Introduced in America, in Canada, United States of America; in Mexico, in Coahuila, State of Mexico, Jalisco, Michoacan, Nuevo Leon, and Sonora (Fig. 2b); to South America; in Asia (far East), South Africa, and Australia. Habitat and ecology: —Ruderal and cropland. Elevation 1900–3000 m. Limestone Andosol, Cambisol, Phaeozem, Planosol, Regosol, and Vertisol soil types. Phenology: —Flowering and fruiting throughout the year. Note: —This blue-flowered species can easily be confused with L. lewisii; however, the size of the plant, leaves, and fruits are larger in L. usitatissimum. Besides, the linear to claviform styles, as well as its habitat, are key characters for differentiating the species. Conservation status: — Linum usitatissimum is the only species of the family in Mexico that is introduced and naturalized. It is considered a crop, ruderal and weed species (Martínez-Orea et al. 2020). Specimens examined: — MEXICO. Coahuila: Saltillo, Invernadero UAAAN Buenavista, 1750 m, 25°21’25”N, 101°02’04”W, 13 May 1986, L. Arce 288 (ANSM!). State of Mexico: Texcoco, 2240 m, 19°29’28”N, 98°52’47”W, 14 August 1976, S.D. Koch 76151 (CHAPA!); Texcoco, Campo Experimental Chapingo, 2250 m, 19°29’00”N, 98°53’00”W, 11 October 1984, G. Vázquez C. 33 (CHAPA!); Villa Guerrero, Entre el Pueblo y la Autopista, 2267 m, 18°59’20.3”N, 98°38’53.9”W, 6 October 2000, H. Vibrans 6781 (CHAPA!). Jalisco: Chapala, Carretera Ocotlán-Atequiza, 1500 m, 20°19’38”N 103°11’08”W, 20 May 1968, L.M.V. de Puga 2727 (IBUG!); Ocotlán, 20°20’45”N, 102°46’12”W, 1 April 1973, J. Fdo. Amador A. 25 (IBUG!); Tepatitlán, 20°48’26”N, 102°46’07”W, 1 December 1977, T. Tejeda 135146 (IBUG!); Zapopan, Villa Universitaria al W de Guadalajara, 1550 m, 20°41’47”N, 103°24’47”W, 15 March 1975, L.M.V. de Puga 17066 (IBUG!). Michoacan: Pátzcuaro, Salida a Uruapan, 2100 m, 19°29’36”N, 101°36’00”W, 20 September 1993, J.M. Escobedo 2649 (IEB!). Nuevo Leon: Galena, Cerro el Potosí cerca de San José de la Joya, 3200 m, 24°53’12.8”N, 100°14’28.6”W, 24 September 2011, E. Estrada et al. 20955 (ANSM!). Sonora: Cajeme, Distrito Guaymas, 28°05’26”N, 110°00’47”W, 18 May 1957, J. Corral 44 (CHAPA!)., Published as part of González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, pp. 141-184 in Phytotaxa 549 (2) on pages 175-176, DOI: 10.11646/phytotaxa.549.2.3, http://zenodo.org/record/6622753, {"references":["Linnaeus, C. (1753) Linum. Species Plantarum 1: 277.","Hudson, W. (1778) Linum angustifolium. Flora Anglica 1: 134.","Miller, P. (1768) Linum humile. The Gardeners Dictionary 2.","Martinez-Orea, Y., Bonilla-Valencia, L., Vazquez-Santos, Y., Romero-Romero, A., Solis-Oberg, S., Santibanez-Andrade, G. & Castillo- Arguero, S. (2020) Grupos funcionales en la dinamica del banco de semillas en un bosque templado de la Ciudad de Mexico, Mexico. Botanical Sciences 98: 487 - 499. https: // doi. org / 10.17129 / botsci. 2584"]}