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5b. Amaranthus graecizans L. subsp. sylvestris (Vill.) Brenan, Watsonia 4: 273. 1961 ≡ Amaranthus sylvestris Vill., Cat. Pl. Jard. Strasb. 111. 1807 ≡ Amaranthus sylvestris Desf. ex Poiret, Tabl. École Bot.: 44. 1804, nom. nud., nom. inval. (Art. 38.2 Ex.1 of the ICN) ≡ Amaranthus graecizans var. sylvestris (Desf.) Asch., Beitr. Fl. Aethiop.: 176. 1867, comb. illeg. ≡ Amaranthus graecizans subsp. sylvestris (Vill.) O.Bolòs & Vigo, Butl. Inst. Catalana Hist. Nat., Secc. Bot. 38(1): 89. 1974 ≡ Amaranthus angustifolius proles sylvestris (Vill.) Thell., Syn. Mitteleur. Fl. [Ascherson & Graebner] 5(1(5)): 300. 1914 ≡ Amaranthus angustifolius subsp. sylvestris (Vill.) Heukels, Geïllustreerde Schoolflora voor Nederland: 170. 1934. Type (lectotype designated by Townsend 1985: 31):— Herb. Tournefort 1849 (P!). Iconography:— Willdenow (1790: Tab. VIII, fig. 16 sub A. viridis), Bayón (2015: 329, Figura 34) Phenology:— Flowering time february. Habitat and elevation:— Human-made habitat (coastal plain), 5–15 m a.s.l. Chromosome number: —2n = 32. Occurrence in Saudi Arabia (Fig. 5): — Jizan, Makkah. Specimina visa selecta:— SAUDI ARABIA, Makkah, Jeddah, s.d., Kruijt 48 (L 1684182!); Jizan, human-made habitat (coastal plain), 5–15 m a.s.l., 17 February 2021, leg. Masrhai et Al-shaye, det. Masrhai, conf. Iamonico (PNUH!, RO!)., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on page 143, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Townsend, C. C. (1985) Amaranthaceae. In: Polhill, R. M. (Ed.) Flora of Tropical East Africa. A. A. Balkema, Rotterdam, pp. 1 - 136.","Willdenow, C. L. (1790) Historia Amaranthorum. Impensis Ziegleri et fil., Turici, 38 pp.","Bayon, N. D. (2015) Revision taxonomica de las especies monoicas de Amaranthus (Amaranthaceae): Amaranthus subg. Amaranthus and Amaranthus subg. Albersia. Ann. Missouri Bot. Garden 101 (2): 261 - 383. https: // doi. org / 10.3417 / 2010080"]}

11. Amaranthus hybridus L., Sp. Pl. 2: 990. 1753 Type (lectotype designated by Townsend 1974: 19):— U.S.A. Habitat in Virginia, Herb. Linn. No. 1117.19 (LINN!, image of the lecyotype is available at http://linnean-online.org/11645/). = Amaranthus chlorostachys Willd., Hist. Amaranth.: 34. 1790. Type (lectotype designated by Iamonico 2016a: 521):— UNSPECIFIED LOCALITY, Hermes s.n. (B-W17521!, image of the lecyotype is available at https://herbarium.bgbm.org/object/BW17521000). = Amaranthus patulus Bertol., Comment. Itin. Neapol. 19. 1837. Type (lectotype designated by Iamonico 2016a: 525):— ITALY. Campania: Napoli al Pasconcello, September 1834, Bertoloni s.n. (BOLO!, image of the lectotype in Iamonico 2916°: Figure 3). = Amaranthus hybridus L. subsp. hybridus var. erythrostachys Moq., Prodr. [A.P. de Candolle] 13(2): 259. 1849. Type (lectotype designated by Iamonico 2016a: 522):— FRANCE. “ Hort. Tol. ”, 1844, sine coll. s.n. (G147762/1!, image of the lectotype available at http://www.ville-ge.ch/musinfo/bd/cjb/chg/adetail.php?id=138993&base=img&lang=en). Description:— Herbs 6–20(–25) dm tall, monoecious, annual (therophyte). Stems erect, glabrous (pubescent in the upper part), green to reddish, often branched. Leaves usually green, ovate to ovate-lanceolate, rhomboidal [(2.0–)3.0– 8.0(–13.0) × (1.0–)1.5–6.0(–6.0) cm], with usually entire margins, apex acute or obtuse, mucronate, base cuneate, usually glabrous, petioled [petiole (1.0–)1.5–4.0(–6.0) cm long]. Synflorescences terminal, panicle-like, the main florescence usually up to 15 cm long (longer than the paraclades), usually green. Floral bracts greenish or yellowish, lanceolate to lanceolate-linear [(2.5–4.5(–6.0) × 1.0– 1.5 mm)], 1.6–2.0 times longer than the perianth, acute, awned, with membranous border abruptly interrupted at the half, margin entire, glabrous. Staminate flowers with 5 tepals, ovate-lanceolate; stamens (4–)5. Pistillate flowers with 5 tepals, ovate to lanceolate [(1.5–)2.0–2.5(–3.0) × 0.5–0.7 mm], with acute and sometimes mucronate apex, median vein usually dark-green; stigmas 3. Fruit usually brown, ellipsoidal [1.5–2.5(–3.5) × 1.0– 1.2 mm], as long as or longer than the perianth, smooth to rugose, dehiscent. Seed lenticular (0.9–1.4 mm in diameter), black to dark reddish-brown. Iconography:— Ardenghi & Parolo (2010: 71, figs. 6b, e), Bayón (2015: 283, Figura 10). Phenology:— Flowering time April (Al-Eisawi & Al-Ruzayza 2015). Habitat and elevation:— Human-made habitat, at 250–300 m a.s.l. (Al-Eisawi & Al-Ruzayza 2015). Chromosome number:— 2n = 32, 34. Alien status:— Neophyte species native to tropical areas of North and Central America, it can be considered as naturalized in Saudi Arabia (Chaudhary 1998). Occurrence in Saudi Arabia (Fig. 14):— Al-Baha, Makkah (Al-Eisawi & Al-Ruzayza 2015), Tabuk (Aljieddani et al. 2021), Bisha (Abbas et al. 2020), and Taif (Abdullah et al. 2017). No finding was done during the filed surveys. Further researches are necessary to verify the distribution of Amaranthus hybridus in the country. Taxonomic annotations:— Amaranthus hybridus is a species characterized in having an high phenotypic variability, especially concerning the features of the flowers. Costea et al. (2001) recognized two subspecies [subsp. hybridus and subsp. quitensis (Kunth) Costea & Carretero] on the basis of the shape of the tepals (ovate and acute in subsp. hybridus, obovate to spathulate tepals and obtuse to truncate in subsp. quitensis). However, one of us (DI) believes that the taxon quitensis is more related to A. retroflexus, at least on the basis of shape and length of the tepal (a study is in progress by DI). In other cases, other taxa (e.g., A. cruentus L. or A. hypochondriacus L.) were accepted as subspecies of A. hybridus (see, e.g. Galasso et al. 2018). Anyway, further several forms were described in the past and a taxonomic revision is still lacking. We here accept the recognition of A. hybridus as separate species from the other member of the aggregate, according to Iamonico (2015)., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on pages 151-152, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Townsend, C. C. (1974) Amaranthaceae. In: Nasir, E. & Ali, S. I. (Eds.) Flora of West Pakistan, vol. 71. Ferozsons Press, Rawalpindi, pp. 1 - 49.","Iamonico, D. (2016 a) Nomenclature survey of the genus AMARANTHUS (AMARANTHACEAE). 3. Names linked to the Italian flora. Plant Biosystems 150 (3): 519 - 531. https: // dx. doi. org / 10.1080 / 11263504.2014.987188","Ardenghi, N. M. G. & Parolo, G. (2010) Primo contributo alla flora esotica della provincia di Sondrio (Lombardia, Italia). Atti del Museo Civico di Storia Naturale di Morbegno 21: 49 - 81.","Bayon, N. D. (2015) Revision taxonomica de las especies monoicas de Amaranthus (Amaranthaceae): Amaranthus subg. Amaranthus and Amaranthus subg. Albersia. Ann. Missouri Bot. Garden 101 (2): 261 - 383. https: // doi. org / 10.3417 / 2010080","Al-Eisawi, D. M. & Al-Ruzayza, S. (2015) The flora of holy Mecca district, Saudi Arabia. International Journal of Biodiversity Conservation 7 (3): 173 - 189. https: // doi. org / 10.5897 / IJBC 2014.0773","Chaudhary, S. A. (1998) Flora of the Kingdom of the Saudi Arabia, vol. 1. Ministry of Agriculture & Water, Riyadh, 692 pp.","Abbas, A. M., Al-Kahtani, M. A., Alfaifi, M. Y., Elbehairi, S. E. I. & Badry, M. O. (2020) Floristic Diversity and Phytogeography of JABAL Fayfa: A Subtropical Dry Zone, South-WestSaudi Arabia. Diversity 12: 345. https: // dx. doi. org / 10.3390 / d 12090345","Abdullah, M. A., Al. Yasee, H., Al-Sudani, Y. & Moneruzaman, M. (2017) Developing weeds of agricultural crops at different levels of heights, in taif area of Saudia Arabia. Bulgarian Journal of Agricultural Science 23 (5): 762 - 769.","Costea, M., Sanders, A. & Waines, G. (2001) Preliminary results towards a revision of the Amaranthus hybridus complex (Amaranthaceae). Sida 19: 931 - 974.","Galasso, G., Bartolucci, F., Peruzzi, L., Ardenghi, N. M. G., Albano, A., Alessandrini, A., Bacchetta, G., Ballelli, S., Baldini Mazzanti, M., Barberis, G., Bernardo, L., Bouvet, D., Bovio, M., Cecchi, L., Del Guacchio, E., Domina, G., Fascetti, S., Gallo, L., Gubellini, L., Guiggi, A., Iamonico, D., Iberite, M., Jimenez-Mejias, P., Lattanzi, E., Marchetti, D., Martinetto, E., Masin, R. R., Medagli, P., Passalacqua, N. G., Peccenini, S., Pennesi, R., Pierini, B., Podda, L., Poldini, L., Prosser, F., Raimondo, F. M., Roma-Marzio, F., Rosati, L., Santangelo, A., Scoppola, A., Scortegagna, S., Selvaggi, A., Selvi, F., Soldano, A., Stinca, A., Wagensommer, R. P., Wilhalm, T. & Conti, C. (2018) An updated checklist of the vascular flora alien to Italy. Plant biosystems 152 (3): 556 - 592. https: // doi. org / 10.1080 / 11263504.2018.1441197"]}

4. Amaranthus viridis L., Sp. Pl., ed. 2. 2: 1405. 1763 Type (lectotype designated by Fawcett & Rendle 1914: 131):—UNKNOWN ORIGIN. Habitat in Europa, Brasilia, Herb. Linn. No. 1117.15 (LINN!, image of the lectotype available at http://linnean-online.org/11641/). Description:— Herbs 1–7(–8) dm tall, monoecious, annual (therophyte). Stems erect, glabrous, green to brownish, branched. Leaves black-green, ovate, rhomboidal [(2.0–4.5) × (1.5–)2.0–7.0 cm], with entire (rarely undulate) margins, apex obtuse or rounded (rarely slightly emarginate) and sometimens mucronate, base usually cuneate, usually glabrous, petioled [petiole 1.5–5.0 cm long]. Synflorescences terminal, spike- or panicle-like (sometimes axillary glomerules also occur), the main florescence 3–4 cm long, green to brown, usually thin (5–7 mm in diameter). Floral bracts yellowish or greenish, ovate to lanceolate [0.5–1.0 × 0.4–0.7 mm], shorter (up to ⅓) than the perianth, acuminate, margin entire, glabrous. Staminate flowers with 3 tepals, ovate; stamens 3. Pistillate flowers with 3 tepals, ovatelanceolate or obovate-spathulate (1.2–1.5 × 0.3–0.6 mm), with rounded apex (sometimes acute), mucronate or not; stigmas (2–)3. Fruit brownish, subglobose [(1.2–)1.4–1.7(–1.9) × 1.4–1.6(–1.8) mm] as long as or slighly longer (up to ¼) than the perianth, clearly rugose, indehiscent. Seed lenticular (0.8–1.2 mm in diameter), black or brownish-black. Iconography:— Chaudhary (1998: 239, Plate. 129b), Bayón (2015: 371, Figura 64). Phenology:— Flowering time february. Habitat and elevation:— Human-made habitat, 400–600 m a.s.l. Chromosome number:— 2n = 34. Alien status:— Neophyte species native to South America, it can be considered as naturalized in Saudi Arabia (see also Chaudhary 1998). Occurrence in Saudi Arabia (Fig. 3):— Al hudud ash Shamaliyah (Osman & El-Ameid Abedin 2019), Bisha (Abbas et al. 2020), Jizan, and Taif (Abdullah et al. 2017). Taxonomic annotation:— The name Amaranthus gracilis Desf. was cited by Mandaville (2011) as synonym of A. viridis. Desfontaines’ name was widely discussed by Iamonico (2016b) who reached to the conclusion that it is a nomen ambiguum published by Desfontaines (1804) as nomen novum pro Chenopodium caudatum Jacq. The latter Jaquin’s name was proposed as nomen rejectendum by Iamonico et al. (2015). Specimina visa selecta:— SAUDI ARABIA, Jizan, human-made habitat, (coastal plain) 5–15 m a.s.l., 17 February 2021, leg. Masrhai et Al-shaye (PNUH), det. Masrhai, conf. Iamonico (RO!)., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on page 141, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Fawcett, W. & Rendle, A. B. (1914) Flora of Jamaica containing descriptions of the flowering plants known from the island, vol. 3. Order of the Trustees of the British Museum, London, 208 pp.","Chaudhary, S. A. (1998) Flora of the Kingdom of the Saudi Arabia, vol. 1. Ministry of Agriculture & Water, Riyadh, 692 pp.","Bayon, N. D. (2015) Revision taxonomica de las especies monoicas de Amaranthus (Amaranthaceae): Amaranthus subg. Amaranthus and Amaranthus subg. Albersia. Ann. Missouri Bot. Garden 101 (2): 261 - 383. https: // doi. org / 10.3417 / 2010080","Osman, A. K. E. & El-Ameid Abedin, M. A. (2019) Floristic diversity of Wadi Ar'ar, Saudi Arabia. Journal of Taibah University for Science 13 (1): 772 - 789. https: // doi. org / 10.1080 / 16583655.2019.1634177","Abbas, A. M., Al-Kahtani, M. A., Alfaifi, M. Y., Elbehairi, S. E. I. & Badry, M. O. (2020) Floristic Diversity and Phytogeography of JABAL Fayfa: A Subtropical Dry Zone, South-WestSaudi Arabia. Diversity 12: 345. https: // dx. doi. org / 10.3390 / d 12090345","Abdullah, M. A., Al. Yasee, H., Al-Sudani, Y. & Moneruzaman, M. (2017) Developing weeds of agricultural crops at different levels of heights, in taif area of Saudia Arabia. Bulgarian Journal of Agricultural Science 23 (5): 762 - 769.","Mandaville, J. P. (2011) Flora of eastern saudi Arabia. Routledge, London, 276 pp.","Iamonico, D. (2016 b) Nomenclature survey of the genus Amaranthus (Amaranthaceae). 4. Detailed questions arising around the name Amaranthus gracilis. Botanica Serbica 40 (1): 61 - 68.","Desfontaines, R. L. (1804) Tableau de l'ecole de Botanique du Museum d'Histoire Naturelle. J. A. Brosson, Paris, 238 pp. https: // doi. org / 10.5962 / bhl. title. 13828","Iamonico, D., Sukhorukov, A. P. & Reveal, J. L. (2015) (2360) Proposal to reject the name Chenopodium caudatum (Amaranthaceae / Chenopodiaceae). Taxon 64 (3): 638 - 639. https: // dx. doi. org / 10.12705 / 643.18"]}

2b. Amaranthus blitum subsp. blitum var. oleraceus (L.) Hook.f., Fl. Brit. India [J.D. Hooker] 4: 721. 1885 ≡ Amaranthus oleraceus L., Sp. Pl., ed. 2. 2: 1403. 1763 ≡ Amaranthus lividus proles oleraceus (L.) Thell. in Asch. & Graebn., Syn. Mitteleur. Fl. [Ascherson & Graebner] 5(1(5)): 321. 1914 ≡ Amaranthus blitum subsp. oleraceus (L.) Costea in Costea & al., Sida 19(4): 984. 2001 Type (lectotype designated by Filias et al. 1980: 150):—ASIA. Habitat in India, Herb. Linn., No. 1117.13 (LINN!, image of the lectotype available at http://linnean-online.org/11639/). Iconography:— Bayón (2015: 307, Figura 22). Chromosome number:— Unknown. Alien status:— The origin of this taxon is uncertain at present. It probably originated from a selection of the var. blitum which was used as cultivated vegetable (see e.g., Costea et al. 2001). However, it does not appear to have been used for this purpose in Saudi Arabia. We consider var. oleraceus as casual in Saudi Arabia. Occurrence in Saudi Arabia:— Var. oleraceus is here considered since it was listed by Thomas (2011). In fact, we did not found this variety during the field survey. Further investigations need to verify its real occurrence in Saudi Arabia., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on page 140, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Filias, F., Gaulliez, R. & Guedes, M. (1980) Amaranthus blitum vs. A. lividus (Amaranthaceae). Taxon 29: 149 - 150. https: // doi. org / 10.2307 / 1219612","Bayon, N. D. (2015) Revision taxonomica de las especies monoicas de Amaranthus (Amaranthaceae): Amaranthus subg. Amaranthus and Amaranthus subg. Albersia. Ann. Missouri Bot. Garden 101 (2): 261 - 383. https: // doi. org / 10.3417 / 2010080","Costea, M., Sanders, A. & Waines, G. (2001) Preliminary results towards a revision of the Amaranthus hybridus complex (Amaranthaceae). Sida 19: 931 - 974.","Thomas, H. (2011) Flora of Saudi Arabia - Checklist. Available from: http: // www. plantdiversityofsaudiarabia. info / Biodiversity-Saudi- Arabia / Flora / Checklist / Cheklist. htm (accessed 29 march 2022)"]}

7a. Amaranthus blitoides var. blitoides Description:— See above. Iconography:— Bayón (2015: 307, Figura 21). Phenology:— Flowering time february. Habitat and elevation:— Human-made habitat (coastal plain), 5–15 m a.s.l. Chromosome number:— 2n = 32, 34. Occurrence in Saudi Arabia (Fig. 7):— Jizan (first record). Alien status:— Neophyte species native to North America, it can be considered as casual in Saudi Arabia. Specimina visa selecta:— SAUDI ARABIA. Jizan, human-made habitat (coastal plain), 5–15 m a.s.l., 17 February 2021, leg. Masrhai et Al-shaye, det. Masrhai, rev. Iamonico (PNUH!, RO!; Fig. 8); ibidem (PNUH!, RO!); ibidem (PNUH!, RO!)., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on page 146, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Bayon, N. D. (2015) Revision taxonomica de las especies monoicas de Amaranthus (Amaranthaceae): Amaranthus subg. Amaranthus and Amaranthus subg. Albersia. Ann. Missouri Bot. Garden 101 (2): 261 - 383. https: // doi. org / 10.3417 / 2010080"]}

Amaranthus L., Sp. Pl. 2: 989. 1753. Type (lectotype designated by Green 1929: 188): Amaranthus caudatus L. Description:— Monoecious or dioecious herbs, usually annual (therophytes), sometimes perennial (hemicryptophytes). Stems erect, ascending, or prostrate, glabrous to tomentose (trichomes uniseriate, whitish to yellowish), green, white, brownish or red, usually branched. Leaves alternate, petioled, with blade lanceolate to ovate, elliptic to deltoid to rhombic; base cuneate to obtuse; apex acute, obtuse, or emarginate, sometimens mucronate; margins entire, sometimens undulate; blade glabrous to pubescent (sometimens hairs only along the veins), with trichomes whitish to yellowish, uniseriate. Synflorescences thyrsoid paraclades arranged in terminal and/or axillary spike- or panicle-like structures or only in axillary glomerules (for details see Iamonico 2015). Bracts 1–5, ovate to lanceolate, with membranous borders thinning to apex or abruptly interrupted at the half of the total length, sometimes keeled; apex acute to obtuse. Flowers unisexual, sessile. Staminate flowers with 3–5 free and more or less equal tepals, ovate to lanceolate, usually glabrous; apex usually acute; margin entire; stamens 3–5, anthers tetrasporangiate with 2 lines of dehiscence, filaments free to the base; pseudostaminodia absent. Pistillate flowers with (0–)2–5 usually free tepals, linear to ovate-lanceolate sometimes spathulate, usually glabrous; apex acute to emarginate (sometimes mucronate); margins entire; one pistil, one ovule, 2–5 stigmas. Fruit dry (dehiscent capsule, or indehiscent utricle), globose to ellipsoid, smooth to strongly rugose on the surface, with often persistent styles; seed one, usually lenticular, smooth to reticulate; embryo annular. General note and diagnostic key:— Twelve non-hybrid species (sixteen taxa, by considering the infraspecific taxa) were here recorded in Saudi Arabia, of which two (A. caudatus and A. tricolor L.) are cultivated only in the country. Four taxa (A. graecizans subsp. graecizans, A. graecizans subsp. sylvestris, A. graecizans subsp. thellungianus, and A. sparganicephalus) are authoctonous, whereas the other ones are aliens, mostly neophytes native to the Americas (Table 2). A diagnostic key of the Amaranthus species occurring in Saudi Arabia follows (the characters of the flowers refer to the pistillate ones, since the features of the staminate flowers have a very low taxonomical value in the genus Amaranthus; see e.g., Mosyakin & Robertson 2003, Iamonico 2015). We include also the two cultivated species (A. caudatus and A. tricolor) which could be found in wild in future. Diagnostic keys for infraspecific taxa of A. blitum L. and A. graecizans are reported after the morphological descriptions of them. 1. Tepals 3...............................................................................................................................................................................................2 - Tepals> 3...........................................................................................................................................................................................7 2. Stem white to white-greenish; bracts spinescent longer than the tepals.............................................................................1. A. albus - Stem never white to white-greenish; bracts not spinescent, shorter than the tepals...........................................................................3 3. Synflorescence spike- or panicle-like.................................................................................................................................................4 - Synflorescence in axillary glomerules................................................................................................................................................6 4 Fruit indehiscent (utricle), as long as or longer than the perianth......................................................................................................5 - Fruit dehiscent (capsule) shorter than the perianth.......................................................................................................... 3. A. tricolor 5. Fruit smooth or sligthly on the surface...................................................................................................................... 2. A. blitum s.lat - Fruit strongly rugose on the surface.................................................................................................................................. 4. A. viridis 6. Fruit shorter than the perianth......................................................................................................................................... 3. A. tricolor 6. Fruit as long as or longer than the perianth........................................................................................................................................8 8. Fruit up to 2.7 mm long 4, never longitudinally sulcate.................................................................................... 5. A. graecizans s.lat - Fruit> than 2.7 mm long, the proximal half longitudinally sulcate............................................................... 6. A. sparganocephalus 7. Tepals usually 4; stem prostrate-diffuse or ascending; synflorescence arranged in axillary glomerules...................... 7. A. blitoides - Tepals 5; stem erect; synflorescence arranged in spike- or panicle-like structures............................................................................ 8 8. Bracts of the first flower in the first cyme metamorphosed into a spine-like structure................................................ 8. A. spinosus - Bracts spine-like absent......................................................................................................................................................................9 9. Terminal synflorescence usually pendulous up to 70 cm long; tepals (at least the inner ones) obovate-spathulate.....9. A. caudatus - Terminal synflorescence always erect; tepals ovate to lanceolate.................................................................................................... 10 10. Bracts up to 2 mm long and always shorter than the tepals............................................................................................10. A. dubius - Bracts> 2 mm long and always longer than the tepals....................................................................................................................11 11. Bracts clearly longer (1.6–2.0 times) than the perianth; tepals with median vein usually dark-green....................... 11. A. hybridus - Bracts as long as or slightly longer (up to 1.5 times) than the perianth; tepals with median vein usually yellow-brown........................................................................................................................................................................................................ 12. A. cruentus

9. Amaranthus caudatus L., Sp. Pl. 2: 990. 1753 Type (lectotype designated by Towsend 1974: 10):—UNKNOWN ORIGIN. Habitat in Perù, Persia, Zeylonia, Herb. Linn. No. 1117.26 (LINN!, image of the lectotype available at http://linnean-online.org/11652/). Description:— Herbs 8–15 dm tall, monoecious, annual (therophyte). Stems erect, glabrous (pubescent in the distal part), red to purple, branched. Leaves red, ovate, rhomboidal 5.0–15.0 × 2.0–8.0 cm), with entire margins, apex obtuse or acute, mucronate, base cuneate, often pubescent, petioled (petiole 1.0–12.0 cm long). Synflorescences terminal, spike-like, up to 60–70 cm long, red to purple, pendulous (terminal florescence 30 cm long or more). Floral bracts greenish to reddish, ovate to lanceolate-linear (3.0–4.0 × 0.8–1.5 mm) longer than the perianth, acute, awned, margin entire, glabrous. Staminate flowers with 5 tepals, ovate; stamens 5. Pistillate flowers with 5 tepals, lanceolate-spathulate (1.0–2.5 × 0.3–1.3 mm), with acute (in this case mucronate) or obtuse (sometimes emarginate) apex; stigmas 3. Fruit brownish, globose (1.5–2.5 × 1.4–1.9 mm), as long as or longer than the perianth, smooth to rugose, dehiscent. Seed lenticular (1.0– 1.5 mm in diameter), dark-brown to brownish-black. Iconography:— Beck (1909: Tab. 297, figures 1–2), Bayón (2015: 277, Figura 6). Phenology:— Flowering time december. Habitat and elevation:— Dry and rocky places, human-made habitat, around 1700 m a.s.l. Chromosome number:— 2n = 34, 68. Alien status:— Neophyte species native to South America (Argentina, Equador, Peru, and Bolivia), it can be considered as casual in Saudi Arabia (Makkah). Occurrence in Saudi Arabia (Fig. 11):— According to Chaudhary (1998: 236) this species would be cultivated only in Saudi Arabia (as ornamental plant). Despite no wild plants were found by us during the field survey, we traced one specimen at IND, so confirming that the species occurs in Saudi Arabia. Specimina visa selecta:— SAUDI ARABIA, Makkah, about 5 km N of Taif, dry, rocky hillside, military base, 1720 m, 11 February 1977, leg. Humbles 100032, det. Johnson (IND0088369!)., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on pages 148-149, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Beck, G. (1909) Icones Florae Germanicae et Helveticae, vol. 24. F. Hofmeister, Lipsiae, 213 pp.","Bayon, N. D. (2015) Revision taxonomica de las especies monoicas de Amaranthus (Amaranthaceae): Amaranthus subg. Amaranthus and Amaranthus subg. Albersia. Ann. Missouri Bot. Garden 101 (2): 261 - 383. https: // doi. org / 10.3417 / 2010080","Chaudhary, S. A. (1998) Flora of the Kingdom of the Saudi Arabia, vol. 1. Ministry of Agriculture & Water, Riyadh, 692 pp."]}

Amaranthus L., Sp. Pl. 2: 989. 1753. Type (lectotype designated by Green 1929: 188): Amaranthus caudatus L. Description:— Monoecious or dioecious herbs, usually annual (therophytes), sometimes perennial (hemicryptophytes). Stems erect, ascending, or prostrate, glabrous to tomentose (trichomes uniseriate, whitish to yellowish), green, white, brownish or red, usually branched. Leaves alternate, petioled, with blade lanceolate to ovate, elliptic to deltoid to rhombic; base cuneate to obtuse; apex acute, obtuse, or emarginate, sometimens mucronate; margins entire, sometimens undulate; blade glabrous to pubescent (sometimens hairs only along the veins), with trichomes whitish to yellowish, uniseriate. Synflorescences thyrsoid paraclades arranged in terminal and/or axillary spike- or panicle-like structures or only in axillary glomerules (for details see Iamonico 2015). Bracts 1–5, ovate to lanceolate, with membranous borders thinning to apex or abruptly interrupted at the half of the total length, sometimes keeled; apex acute to obtuse. Flowers unisexual, sessile. Staminate flowers with 3–5 free and more or less equal tepals, ovate to lanceolate, usually glabrous; apex usually acute; margin entire; stamens 3–5, anthers tetrasporangiate with 2 lines of dehiscence, filaments free to the base; pseudostaminodia absent. Pistillate flowers with (0–)2–5 usually free tepals, linear to ovate-lanceolate sometimes spathulate, usually glabrous; apex acute to emarginate (sometimes mucronate); margins entire; one pistil, one ovule, 2–5 stigmas. Fruit dry (dehiscent capsule, or indehiscent utricle), globose to ellipsoid, smooth to strongly rugose on the surface, with often persistent styles; seed one, usually lenticular, smooth to reticulate; embryo annular. General note and diagnostic key:— Twelve non-hybrid species (sixteen taxa, by considering the infraspecific taxa) were here recorded in Saudi Arabia, of which two (A. caudatus and A. tricolor L.) are cultivated only in the country. Four taxa (A. graecizans subsp. graecizans, A. graecizans subsp. sylvestris, A. graecizans subsp. thellungianus, and A. sparganicephalus) are authoctonous, whereas the other ones are aliens, mostly neophytes native to the Americas (Table 2). A diagnostic key of the Amaranthus species occurring in Saudi Arabia follows (the characters of the flowers refer to the pistillate ones, since the features of the staminate flowers have a very low taxonomical value in the genus Amaranthus; see e.g., Mosyakin & Robertson 2003, Iamonico 2015). We include also the two cultivated species (A. caudatus and A. tricolor) which could be found in wild in future. Diagnostic keys for infraspecific taxa of A. blitum L. and A. graecizans are reported after the morphological descriptions of them. 1. Tepals 3...............................................................................................................................................................................................2 - Tepals> 3...........................................................................................................................................................................................7 2. Stem white to white-greenish; bracts spinescent longer than the tepals.............................................................................1. A. albus - Stem never white to white-greenish; bracts not spinescent, shorter than the tepals...........................................................................3 3. Synflorescence spike- or panicle-like.................................................................................................................................................4 - Synflorescence in axillary glomerules................................................................................................................................................6 4 Fruit indehiscent (utricle), as long as or longer than the perianth......................................................................................................5 - Fruit dehiscent (capsule) shorter than the perianth.......................................................................................................... 3. A. tricolor 5. Fruit smooth or sligthly on the surface...................................................................................................................... 2. A. blitum s.lat - Fruit strongly rugose on the surface.................................................................................................................................. 4. A. viridis 6. Fruit shorter than the perianth......................................................................................................................................... 3. A. tricolor 6. Fruit as long as or longer than the perianth........................................................................................................................................8 8. Fruit up to 2.7 mm long 4, never longitudinally sulcate.................................................................................... 5. A. graecizans s.lat - Fruit> than 2.7 mm long, the proximal half longitudinally sulcate............................................................... 6. A. sparganocephalus 7. Tepals usually 4; stem prostrate-diffuse or ascending; synflorescence arranged in axillary glomerules...................... 7. A. blitoides - Tepals 5; stem erect; synflorescence arranged in spike- or panicle-like structures............................................................................ 8 8. Bracts of the first flower in the first cyme metamorphosed into a spine-like structure................................................ 8. A. spinosus - Bracts spine-like absent......................................................................................................................................................................9 9. Terminal synflorescence usually pendulous up to 70 cm long; tepals (at least the inner ones) obovate-spathulate.....9. A. caudatus - Terminal synflorescence always erect; tepals ovate to lanceolate.................................................................................................... 10 10. Bracts up to 2 mm long and always shorter than the tepals............................................................................................10. A. dubius - Bracts> 2 mm long and always longer than the tepals....................................................................................................................11 11. Bracts clearly longer (1.6–2.0 times) than the perianth; tepals with median vein usually dark-green....................... 11. A. hybridus - Bracts as long as or slightly longer (up to 1.5 times) than the perianth; tepals with median vein usually yellow-brown........................................................................................................................................................................................................ 12. A. cruentus, Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on page 137, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Green, M. L. (1929) Amaranthus caudatus L. In: Hitchcock, A. S. (Ed.) Nomenclature. Proposals by British Botanists. Wyman & Sons, London, p. 188.","Mosyakin, S. L. & Robertson, K. R. (2003) Amaranthus L. In: Flora of North America Editorial Committee (Org) Flora of North America North of Mexico (Magnoliophyta: Caryophyllidae, part 1), vol. 4. Oxford University Press, Oxford, pp. 410 - 435."]}

8. Amaranthus spinosus L., Sp. Pl. 2: 991. 1753 Type (lectotype designated by Fawcett & Rendle 1914: 103):—ASIA. Habitat in Indiis, Herb. Linn. No. 1117.27 (LINN!, image of the lectotype available at http://linnean-online.org/11653/). Description:— Herbs 1–85(–120) dm tall, monoecious, annual (therophyte), rarely biennial. Stems usually erect, ± glabrous (sometimes sparsely pubescent in the inflorescence region), white to white-greenish, much branched. Leaves green (usually pale green), ovate, elliptic to spathulate (3.5–6.0 × 1.5–3.0 cm in the main axis, greater than the leaves on the branches), often with undulate margins (sometimes with a white marginal vein), apex obtuse and mucronate, base cuneate, glabrous (rarely pubescent on the veins), petioled (petiole 1.6–3.0 cm long). Synflorescences arranged in axillary glomerules, light green. Floral bracts greenish, ovate-lanceolate [(2.0–)3.0–4.0(–6.0) × 0.3–0.6 mm], 2(–2.5) times longer than the perianth, awned, margin entire, glabrous. Staminate flowers with 3 tepals, lanceolate; stamens 3. Pistillate flowers with 3 tepals, linear to lanceolate [0.9–1.1 × 0.3–0.4(–0.5) mm], with acute apex; stigmas 3. Fruit brownish-black, ellipsoidal [(1.2–)1.4–1.8 × 1.0–1.2(–1.4) mm], as long as or slightly longer than the perianth, rugose when dry, dehiscent. Seed lenticular [(0.8–)0.9–1.1(–1.3) mm in diameter], black to brownish-black. Iconography:— Beck (1909: Tab. 297, figures 3–5); Chaudhary (1998: Plate. 127g –j), Bayón (2015: 296, Figura 15). Phenology:— Flowering time June (Al-Turki et al. 2000). Habitat and elevation:— Human-made habitat, about sea level (Al-Turki et al. 2000). Chromosome number:— 2n = 34 (Al-Turki et al. 2000: 341), 68. Alien status:— Neophyte species native to Neotropics, it can be considered as casual in Saudi Arabia (see also Chaudhary 1998). Occurrence in Saudi Arabia (Fig. 10):— Bisha (Abbas et al. 2020), Jizan (Al-Turki et al. 2000, Aljieddani et al. 2021). No finding was done during the filed surveys. Further researches are necessary to verify the distribution of A. spinosus in the country., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on page 148, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Fawcett, W. & Rendle, A. B. (1914) Flora of Jamaica containing descriptions of the flowering plants known from the island, vol. 3. Order of the Trustees of the British Museum, London, 208 pp.","Beck, G. (1909) Icones Florae Germanicae et Helveticae, vol. 24. F. Hofmeister, Lipsiae, 213 pp.","Chaudhary, S. A. (1998) Flora of the Kingdom of the Saudi Arabia, vol. 1. Ministry of Agriculture & Water, Riyadh, 692 pp.","Bayon, N. D. (2015) Revision taxonomica de las especies monoicas de Amaranthus (Amaranthaceae): Amaranthus subg. Amaranthus and Amaranthus subg. Albersia. Ann. Missouri Bot. Garden 101 (2): 261 - 383. https: // doi. org / 10.3417 / 2010080","Al-Turki, T. A., Filfilan, S. A. & Mehmood, S. F. (2000) A cytological study of flowering plants from Saudi Arabia. Willdenowia 30: 339 - 358. https: // doi. org / 10.3372 / wi. 30.30211","Abbas, A. M., Al-Kahtani, M. A., Alfaifi, M. Y., Elbehairi, S. E. I. & Badry, M. O. (2020) Floristic Diversity and Phytogeography of JABAL Fayfa: A Subtropical Dry Zone, South-WestSaudi Arabia. Diversity 12: 345. https: // dx. doi. org / 10.3390 / d 12090345"]}

12. Amaranthus cruentus L., Syst. Nat., ed. 10. 2: 1269. 1759 Type (lectotype designated by Townsend 1974: 12):— CHINA. Habitat in China, Herb. Linn. No. 1117.25 (LINN!, image of the lectotype available at http://linnean-online.org/11651/). = Amaranthus flavus L., Syst. Nat., ed. 10. 2: 1269. 1759. Type (lectotype designated by Iamonico 2014a: 147):—UNKNOWN ORIGIN. Herb. Linn. No. 1117.23 (LINN!, image of the lectotype available at http://linnean-online.org/11649/). = Amaranthus paniculatus L., Sp. Pl., ed. 2. 2: 1406. 1763. Type (lectotype designated by El Hadidi & El Hadidy 1981: 37):—AMERICA. Habitat in America, Herb. Linn. No. 1117.20 (LINN!, image of the lectotype available at http://linnean-online.org/11646/). = Amaranthus sanguineus L., Sp. Pl., ed. 2. 2: 1407. 1763. Type (lectotype designated by Iamonico 2014a: 148):—UNKNOWN ORIGIN. Herb. Linn. No. 1117.21 (LINN!, image of the lectotype available at http://linnean-online.org/11647/). Description:— Herbs 5–14 dm tall, monoecious, annual (therophyte). Stems erect, ± glabrous (slightly pubescent in the upper part), red or green, often distally branched. Leaves usually green, ovate to ovate-lanceolate, rhomboidal [(3.0–)5.0–12.0(–14.0) × (1.5–)3.0–6.0(–7.0) cm], with entire margins, apex acute or obtuse (sometimes slightly emarginate), mucronate, base cuneate, glabrous or slightly pubescent, petioled (petiole 1.5–10.0 cm long). Synflorescences terminal, panicle-like, the main florescence up to 15 cm long (longer than the paraclades), red or green. Floral bracts green or greenish, lanceolate (2.0–3.5 × 0.8–1.3 mm), 1.0–1.5 longer than the perianth, acute, awned, with membranous border abruptly interrupted at the half, margin entire, glabrous. Staminate flowers with 5 tepals, ovate-lanceolate; stamens (4–)5. Pistillate flowers with 5 tepals, ovate-lanceolate [(1.5–)2.0–2.5(–3.0) × 0.6–1.5 mm], with acute and sometimes mucronate apex, median vein usually yellow-brown; stigmas 3. Fruit brown, ellipsoidal (2.0–2.5 × 1.4–1.6 mm), longer than the perianth, smooth to slightly rugose, dehiscent. Seed lenticular (1.2–1.6 mm in diameter), dark-brown to reddish-brown. Iconography:— Willdenow (1790: Tab. II fig. 4, sub A. paniculatus), Beck (1909: Tab. 296, figures 3–4, sub Euxolus patulus), Bayón (2015: 280, Figura 7). Chromosome number:— 2n = 32, 34. Alien status:— Neophyte species native to Central America, it can be considered as naturalized in Saudi Arabia (Chaudhary 1998). Occurrence in Saudi Arabia:— Chaudhary (1998) indicated this species [sub Amaranthus hybridus subsp. cruenthus (L.) Thell.] in “the southwest of Saudi Arabia”, without further data about the localities in which it occurs. No finding was done during the filed surveys. Further researches are necessary to verify the distribution of A. cruentus in the country. Taxonomic annotations:— Amaranthus cruentus is quite variable from the morphological point of view, especially concerning the surface of the leaf blade (simple green, green with a white band arch-shaped, or green with a central red spot), the structure of the synflorescences (the paraclades can be erect to patent), and the colour of the stem and synflorescence (from green to red or dark-red). Some cultivars (A. cruentus is also used as ornamental plant), especially those with dark-red synflorescences, can be confused with some forms of A. hypochondriacus, but the two species differ each other by the characters of the bracts (see Iamonico 2015)., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on pages 152-153, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Townsend, C. C. (1974) Amaranthaceae. In: Nasir, E. & Ali, S. I. (Eds.) Flora of West Pakistan, vol. 71. Ferozsons Press, Rawalpindi, pp. 1 - 49.","Iamonico, D. (2014 a) Lectotypification of Linnaean names in the genus Amaranthus L. (Amaranthaceae). Taxon 63: 146 - 150. https: // doi. org / 10.12705 / 631.34","El Hadidi, N. & El Hadidy, A. M. H. (1981) Flora of Egypt. Amaranthaceae Juss. Taeckholmia, Additional Series 1 (2): 1 - 8.","Willdenow, C. L. (1790) Historia Amaranthorum. Impensis Ziegleri et fil., Turici, 38 pp.","Beck, G. (1909) Icones Florae Germanicae et Helveticae, vol. 24. F. Hofmeister, Lipsiae, 213 pp.","Bayon, N. D. (2015) Revision taxonomica de las especies monoicas de Amaranthus (Amaranthaceae): Amaranthus subg. Amaranthus and Amaranthus subg. Albersia. Ann. Missouri Bot. Garden 101 (2): 261 - 383. https: // doi. org / 10.3417 / 2010080","Chaudhary, S. A. (1998) Flora of the Kingdom of the Saudi Arabia, vol. 1. Ministry of Agriculture & Water, Riyadh, 692 pp."]}

5a. Amaranthus graecizans L. subsp. graecizans Iconography:— Beck (1909: Tab. 299, figures 1–7, sub A. angustifolius). Phenology:— Flowering time february. Habitat and elevation:— Human-made habitat (coastal plain), 5–15 m a.s.l. Chromosome number:— 2n = 32 (Baquar & Olusi 1988). Occurrence in Saudi Arabia: — Jizan. Specimina visa selecta (Fig. 4):— SAUDI ARABIA, Jizan, human-made habitat (coastal plain), 5–15 m a.s.l., 17 February 2021, leg. Masrhai et Al-shaye (PNUH), det. Masrhai, conf. Iamonico (RO!)., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on pages 142-143, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Beck, G. (1909) Icones Florae Germanicae et Helveticae, vol. 24. F. Hofmeister, Lipsiae, 213 pp.","Baquar, S. R. & Olusi, O. O. (1988) Cytomorphological and phylogenetic studies of the genus Amaranthus from Nigeria. Kromosomo 51 - 52: 1665 - 1674."]}

7. Amaranthus blitoides S.Watson, Proc. Amer. Acad. Arts 12: 273. 1877 Type (lectotype designated by Fernald 1945: 139):— U.S.A. Iowa: Ames, gravelly or sandy soils especially around buildings and along roads, Bessey s.n. (GH00036983!, image of the lectotype available at https://kiki.huh.harvard.edu/databases/specimen_search.php? mode=details&id=58020). Description:— Herbs (0.4–)1–5 (rarely up to 10) dm tall, monoecious, annual (therophyte). Stems prostrate-ascending, glabrous (rarely sparsely pubescent), pale green to brown, branched. Leaves usually green (sometimes with a central whitish spot), oblong-lanceolate to obovate-spathulate [1.0–3.0(–4.0) × (0.3–)0.5–1.0(–1.5) cm], sometimes fleshy, with entire or undulate margins, apex acute or rounded, often mucronate, base cuneate, glabrous, with marginal white vein, petioled (petiole 0.5–1.8 cm long). Synflorescences arranged in axillary glomerules, reddish or green. Floral bracts green or greenish, ovate to lanceolate (1.3–3.0 × 0.4–0.7 mm), shorter than the longest perianth segments, acute, margin entire, glabrous. Staminate flowers with 3(–4) tepals, ovate to lanceolate; stamens 3. Pistillate flowers with (4–)5 unequal tepals, lanceolate, elliptic [the greater 1.5–2.5(–3.5) × (0.7–)1.0– 1.2 mm], with acute to acuminate, and mucronate apex; stigmas 3. Fruit brown or reddish, ellipsoidal (2.0–2.2 × 1.0– 1.4 mm), as long as or longer than the tepals, usually smooth, dehiscent. Seed lenticular (1.5–1.7 mm in diameter), black. Occurrence in Saudi Arabia:— Jizan [first record, var. blitoides (see below)], Makkah (Iamonico 2016c)., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on page 145, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Fernald, M. L. (1945) Botanical specialities of the Seward Forest and adjacent Areas of Southeastern Virginia. Rhodora 47: 93 - 142.","Iamonico, D. (2016 c) Nomenclature survey of the genus Amaranthus (Amaranthaceae). 5. Moquin-Tandon's names. Phytotaxa 273 (2): 81 - 114. https: // doi. org / 10.11646 / phytotaxa. 273.2.1"]}

2a. Amaranthus blitum subsp. blitum var. blitum Iconography:— Beck (1909: Tab. 300). Phenology:— Flowering time february to april (see also Al-Eisawi & Al-Ruzayza 2015). Habitat and elevation:— Human-made habitat on sandy soils, 250–580 m a.s.l. (see also (Al-Eisawi & AlRuzayza 2015). Chromosome number:— 2n = 34. Alien status:— Archeophyte species native to to Mediterranean area and other parts of Europe, it can be considered as naturalized in Saudi Arabia (see also Chaudhary et al. 1981). Occurrence in Saudi Arabia (Fig. 2):— Hail (El-Ghanim et al. 2010), Makkah (Al-Eisawi & Al-Ruzayza 2015), Riyhad (our investigation). Specimina visa selecta:— SAUDIA ARABIA, Riyadh, sandy soil, 623 m a.s.l., 11 February 2021, leg. Hassan et Alali, det. Iamonico (PNUH!); ibidem (RO!)., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on pages 139-140, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Beck, G. (1909) Icones Florae Germanicae et Helveticae, vol. 24. F. Hofmeister, Lipsiae, 213 pp.","Al-Eisawi, D. M. & Al-Ruzayza, S. (2015) The flora of holy Mecca district, Saudi Arabia. International Journal of Biodiversity Conservation 7 (3): 173 - 189. https: // doi. org / 10.5897 / IJBC 2014.0773","Chaudhary, S. A., Parker, C. & Kasasian, L. (1981) Weeds of central, southern and eastern Arabian Peninsula. Tropical Pest Management 27 (2): 181 - 190. https: // doi. org / 10.1080 / 09670878109413649","El-Ghanim, W. M., Hassan, L. F., Gala, T. M. & Badr, A. (2010) Floristic composition and vegetation analysis in Hail region north of central Saudi Arabia. Saudi Journal of Biological Science 17 (2): 119 - 128. https: // doi. org / 10.1016 / j. sjbs. 2010.02.004"]}

1. Amaranthus albus L., Syst. Nat., ed. 10. 2: 1268. 1759 Type (lectotype designated by Raus 1997: 143):—NORTH AMERICA. Habitat in Philadelphiae maritimis, Herb. Linn. No. 1117.1 (LINN!, image of the lectotype available at http://linnean-online.org/11627/). Description:— Herbs 1–85(–120) dm tall, monoecious, annual (therophyte), rarely biennial. Stems usually erect, ± glabrous (sometimes sparsely pubescent in the inflorescence region), white to white-greenish, much branched. Leaves green (usually pale green), ovate, elliptic to spathulate (3.5–6.0 × 1.5–3.0 cm in the main axis, greater than the leaves on the branches), often with undulate margins (sometimes with a white marginal vein), apex obtuse and mucronate, base cuneate, glabrous (rarely pubescent on the veins), petioled (petiole 1.6–3.0 cm long). Synflorescences arranged in axillary glomerules, light green. Floral bracts greenish, ovate-lanceolate [(2.0–)3.0–4.0(–6.0) × 0.3–0.6 mm], 2(–2.5) times longer than the perianth, awned, margin entire, glabrous. Staminate flowers with 3 tepals, lanceolate; stamens 3. Pistillate flowers with 3 tepals, linear to lanceolate [0.9–1.1 × 0.3–0.4(–0.5) mm], with acute apex; stigmas 3. Fruit brownish-black, ellipsoidal [(1.2–)1.4–1.8 × 1.0–1.2(–1.4) mm], as long as or slightly longer than the perianth, rugose when dry, dehiscent. Seed lenticular [(0.8–)0.9–1.1(–1.3) mm in diameter], black to brownish-black. Iconography:— Chaudhary (1998: 245, Plate. 126a–e), Bayón (2015: 304, Figura 19). Phenology:— Flowering time April (Al-Eisawi & Al-Ruzayza 2015). Habitat and elevation:— Human-made habitat, at about 300 m a.s.l. (Al-Eisawi & Al-Ruzayza 2015). Chromosome number:— 2n = 32, 34. Alien status:— Neophyte species native to North America, it can be considered as invasive in Saudi Arabia (see Aljeddani et al. 2021). Occurrence in Saudi Arabia (Fig. 1):— Jizan, Qassim (El-Ghazali & Al-Soqeer 2013), Makkah (Al-Eisawi & Al-Ruzayza 2015), Tabuk and Taif (Aljieddani et al. 2021). No finding was done during the field surveys. Further researches are necessary to verify the distribution of Amaranthus albus in the country., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on page 138, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Raus, Th. (1997) Amaranthus L. In: Strid, A. & Tan, K. (Eds.) Flora Hellenica vol. 1. Koeltz Scientific Books, Konigstein, pp. 138 - 146.","Chaudhary, S. A. (1998) Flora of the Kingdom of the Saudi Arabia, vol. 1. Ministry of Agriculture & Water, Riyadh, 692 pp.","Bayon, N. D. (2015) Revision taxonomica de las especies monoicas de Amaranthus (Amaranthaceae): Amaranthus subg. Amaranthus and Amaranthus subg. Albersia. Ann. Missouri Bot. Garden 101 (2): 261 - 383. https: // doi. org / 10.3417 / 2010080","Al-Eisawi, D. M. & Al-Ruzayza, S. (2015) The flora of holy Mecca district, Saudi Arabia. International Journal of Biodiversity Conservation 7 (3): 173 - 189. https: // doi. org / 10.5897 / IJBC 2014.0773","Aljeddani, G. S., Al-Harbi, N. A., Al-Qathani, S. M., Al-Absy, K. M., Abdullatif, B. M. & Dahan, T. N. (2021) Inventory of some introduced and invasive plant species in some governorates of the Kingdom of Saudi Arabia. Applied Ecology and Environmental Research 19 (6): 4373 - 4388. https: // doi. org / 10.15666 / aeer / 1906 _ 43734388","El-Ghazali, G. E. B. & Al-Soqeer, A. R. A. (2013) A Checklist of the Weed Flora of Qassim Region, Saudi Arabia. Australian Journal of Basic and Applied Science 7 (2): 900 - 905."]}

3. Amaranthus tricolor L., Sp. Pl. 2: 989. 1753 Type (lectotype designated by Townsend 1974: 14):—ASIA. Habitat in India, Herb. Linn. No. 1117.7 (LINN!, image of the lectotype available at https://linnean-online.org/11633/). = Amaranthus melancholicus L., Sp. Pl. 2: 989. 1753. ≡ Amaranthus tricolor var. melancholicus (L.) Lam. & Monnet, Encycl. [J. Lamarck & al.] 1: 115. 1783. Type (lectotype designated by Townsend 1994: 11):—ASIA. Habitat in India, Herb. Linn., No. 1117.4 (LINN!, image of the lectotype available at http://linnean-online.org/11630/). = Amaranthus tristis L., Sp. Pl. 2: 989. 1753. ≡ Amaranthus tricolor var. tristis (L.) Thell. in Asch. & Graebn., Syn. Mitteleur. Fl. [Ascherson & Graebner] 5: 274. 1914. ≡ Amaranthus tricolor subsp. tristis (L.) Aellen in Hegi, Ill. Fl. Mitt.- Eur. 3(2): 495. 1959. Type (lectotype designated by Iamonico 2014: 149):—ASIA. Habitat in China, Herb. Linn., No. 1117.11 (LINN!, image of the lectotype available at http://linnean-online.org/11637/). = Amaranthus mangostanus L., Cent. Pl. I. 32. 1755. ≡ Amaranthus tricolor var. mangostanus (L.) Thell. in Asch. & Graebn. Syn. Mitteleur. Fl. [Ascherson & Graebner] 5: 274. 1914. ≡ Amaranthus tricolor subsp. mangostanus (L.) Aellen, in Hegi, Ill. Fl. Mitt.- Eur. 3(2): 495. 1959. Type (lectotype designated by Iamonico 2014a: 147):—ASIA. Habitat in India, Herb. Linn., No. 1117.10 (LINN!, image of the lectotype available at http://linnean-online.org/11636/). = Amaranthus polygamus L., Cent. Pl. I. 32. 1755. ≡ Amaranthus tricolor subsp. tristis var. polygamus (L.) Aellen in Hegi, Ill. Fl. Mitt.- Eur. 3(2): 495. 1959. Type (lectotype designated by Iamonico 2014a: 148):—ASIA. Habitat in India, Herb. Linn., No. 1117.9 (LINN!, image of the lectotype available at http://linnean-online.org/11635/). Description:— Herbs 8–10 dm tall, monoecious, annual (therophyte). Stems erect or ascending, ± glabrous, green or red, branched (rarely simple). Leaves green, red, red-purpureus or red-yellow mixed, ovate-rhomboidal (4.0–12.0) × 1.4–6.0), with usually entire margins, apex obtuse to emarginate, often mucronate, base cuneate, glabrous, petioled (petiole 2–6 cm long). Synflorescences arranged in axillary glomerules and terminal spike-like, green to reddish. Floral bracts, usually greenish, deltoid-ovate (5.0–6.0 × 0.8–1.8 mm) as long as the perianth, awned, margin entire, glabrous. Staminate flowers with 3 tepals, ovate to lanceolate, apex acute, awned; stamens 3. Pistillate flowers with 3 tepals, ovate (3.0–5.0 × 1.5–2.5 mm); stigmas 2–3. Fruit brown, subglobose to ellipsoidal (2.0–2.5 × 0.8–1.3 mm), shorter than the perianth, rugose, dehiscent. Seed lenticular (about 1.0 mm in diameter), black or brown. Iconography:— Chaudhary (1998: 245, Plate. 127a–f), Bayón (2015: 368, Figura 61). Chromosome number:— 2n = 34, 68, 85. Occurrence in Saudi Arabia:— Cultivated only in Saudi Arabia according to Chaudhary (1998: 238). No wild plants were found by us during the field survey., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on page 140, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Townsend, C. C. (1974) Amaranthaceae. In: Nasir, E. & Ali, S. I. (Eds.) Flora of West Pakistan, vol. 71. Ferozsons Press, Rawalpindi, pp. 1 - 49.","Townsend, C. C. (1994) Amaranthacees. In: Bosser, J., Cadet, T., Gueho, J. & Marais, W. (Eds.) Flore des Mascareignes: La Reunion, Maurice, Rodrigues, vol. 142. Royal Botanic Gardens, Kew, pp. 1 - 32.","Iamonico, D. (2014 a) Lectotypification of Linnaean names in the genus Amaranthus L. (Amaranthaceae). Taxon 63: 146 - 150. https: // doi. org / 10.12705 / 631.34","Chaudhary, S. A. (1998) Flora of the Kingdom of the Saudi Arabia, vol. 1. Ministry of Agriculture & Water, Riyadh, 692 pp.","Bayon, N. D. (2015) Revision taxonomica de las especies monoicas de Amaranthus (Amaranthaceae): Amaranthus subg. Amaranthus and Amaranthus subg. Albersia. Ann. Missouri Bot. Garden 101 (2): 261 - 383. https: // doi. org / 10.3417 / 2010080"]}

10. Amaranthus dubius Mart. ex Thell., Fl. Adv. Montpell.: 203. 1912 Type (neotype designated by Townsend 1974: 471–472):— GERMANY. Herbairum Regio Monacense, ex horto Erlangensis, s.d., s.c. s.n. (M0107382!, image of the neotype available at https://plants.jstor.org/stable/viewer/10.5555/al.ap.specimen. m0107382?loggedin=true). = Amaranthus tristis var. xanthostachys Moq., Prodr. [A. P. de Candolle] 13(2): 260. 1849 ≡ Amaranthus dubius var. xanthostachys (Moq.) Thell. in Asch. & Graebn., Syn. Mittel-Eur. Fl. 5: 266. 1914. Type (neotype designated by Iamonico 2016c: 104): UNKNOWN ORIGIN. Herbarium Requien, s.d., s.coll. s.n. (P 04021942!, image of the neotype is available at http://mediaphoto.mnhn.fr/media/14494899601942MO7c2qCCiZJWunt). Description:— Herbs 3–10 dm tall, monoecious, annual (therophyte). Stems erect, glabrous, green, branched. Leaves green, ovate, ± rhomboidal (2.0–)3.0–10.0 × (1.5–)2.0–6.0 cm, with entire margins, apex obtuse, mucronate, base cuneate, glabrous, petioled (petiole 0.8–5.5 cm long). Synflorescences terminal, panicle-like, green to yellowhish. Floral bracts greenish-yellowhish, lanceolate (1.2–2.0 mm long) shorter than the perianth, acute, awned, margin entire, glabrous. Staminate flowers with 5 tepals, ovate; stamens 5. Pistillate flowers with 5 tepals, oblong-spathulate (1.5–2.0) × 0.5–1.0 mm), with acute and mucronate apex; stigmas 3. Fruit brownish, ovoid (1.5–2.0 × 1.0– 1.5 mm), shorter than the perianth, smooth to slightly rugose, dehiscent. Seed lenticular (0.8–1.0 mm in diameter), dark-brown to black. Iconography:— Bayón (2015: 280, Figura 8). Phenology:— Flowering time february. Habitat and elevation:— Human-made habitat (coastal plain), 5–15 m a.s.l. Chromosome number:— 2n = 64 (Behera & Patnaik 1982, Baquar & Olusi 1988, Ugborogho & Oyelana 1992, Greizerstein & Poggio 1994). Alien status:— Neophyte species native to South America, it can be considered as casual in Saudi Arabia. Occurrence in Saudi Arabia (Fig. 12):— Our collections (Jizan) represent the first records of Amaranthus dubius in Saudi Arabia. Nomenclatural notes on Amaranthus dubius:— The name Amaranthus dubius was published for the first time by Martius (1814: 197) who did not reported any diagnosis [only the symbols “*” (that means “ significat plantam, de qua anno 1813 non nisi semen adfuit ”), and “†” (that means “ nomen plantae nondum extra omnem dubitationem positum ”) were indicated (see Martius 1814: 3). As a consequence, Martius’ name is a nomen nudum and invalid from the nomenclatural point of view (Art. 38.2 Ex.1 of ICN). Moquin-Tandon (1849: 260), in his treatment of Amaranthaceae in Candolle Prodromus, reported “ A. dubius Mart. Hort. Erlang. 1814, p. 197 ” as synonym of A. tristis L. and, again, this name cannot be considered as valid according to the Art. 36.1b of ICN. Finally, Thellung (1912: 203) validly published the Martius’ name providing a diagnosis partially taken from Moquin-Tandon (1849, “ calyce vix bracteas superante…sepala oblonga, obtusa, mucronulata…Stam 5, interdum 4, raro 3 ”). Thellung (1912: 203) further indicated the provenance (“ Am. trop. … Indes occ. … Afr. trop.... Afr. trop. … mais peut-être seulement à l’etat d’introduction récente ”) and a reference to Seubert’s Amaranthus tristis (Seubert 1864: 237–238). Note, however, that Seubert (1864) described A. tristis in having “bracteis perogonium subaequantibus” which is a character that contrasts the current concept of A. dubius. In fact, this latter species can be easily identified, among the species belonging to the subgen. Amaranthus sensu Mosyakin & Robertson (1996), by the lenght of its bracts which are clearly shorter than the perianth (see also Mosyakin & Robertson 2003). According to the description given by Seubert (1864: 237–238), the species appears to be the real Linnaean A. tristis, a name that is currently considered as heterotypic synonym of A. tricolor (see Iamonico, 2014a: 148–149). The typification of the name Amaranthus dubius has to be addressed in searching Martius’ collection which, according to HUH Index of Botanists (2013 -onwards), is preserved at the herbaria BR and M. No specimen of original material we traced at M. On the other hand, we traced three specimens at BR bearing labels reporting “HERBARIUM MARTII” (collected before 1806, July 20, 1827 and 1864). However, the “HERBARIUM MARTII” is in contrast with Martius’ so-called “private herbarium” which includes all specimens he received from others but not collected by him himself, and that was given to BR after his death (H. Esser pers. comm.). So, just because there is a label head “HERBARIUM MARTII”, it does not mean the specimen was collected by Martius, it just shows that it had been in his possession (H. Esser pers. comm.). As a consequence, we cannot be sure that the three BR specimens found are part of the original material for the name Amaranthus dubius. No further specimen, useful for the lectotypification purpose, were found. So, a neotypification is required according to the Art. 9.8 of ICN and we here confirm the proposal by Townsend (1974: 471–472) who neotypified the name using a specimen included in the Schwaegrichen’s collection at M (barcode M0107382). Specimina visa selecta:— SAUDI ARABIA, Jizan, human-made habitat (coastal plain), 5–15 m a.s.l., 17 February 2021, leg. Masrhai et Al-shaye, det. Masrhai, conf. Iamonico (PNUH!, RO!; Fig. 13); ibidem (PNUH!, RO!); ibidem (PNUH!, RO!); ibidem (PNUH!, RO!)., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on pages 149-150, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Townsend, C. C. (1974) Amaranthaceae. In: Nasir, E. & Ali, S. I. (Eds.) Flora of West Pakistan, vol. 71. Ferozsons Press, Rawalpindi, pp. 1 - 49.","Iamonico, D. (2016 c) Nomenclature survey of the genus Amaranthus (Amaranthaceae). 5. Moquin-Tandon's names. Phytotaxa 273 (2): 81 - 114. https: // doi. org / 10.11646 / phytotaxa. 273.2.1","Bayon, N. D. (2015) Revision taxonomica de las especies monoicas de Amaranthus (Amaranthaceae): Amaranthus subg. Amaranthus and Amaranthus subg. Albersia. Ann. Missouri Bot. Garden 101 (2): 261 - 383. https: // doi. org / 10.3417 / 2010080","Behera, B. & Patnaik, S. N. (1982) Genome analysis of Amaranthus dubius Mart. ex Thell. through the study of Amaranthus spinosus × A. dubius hybrids. Cytologia 47: 379 - 389. https: // doi. org / 10.1508 / cytologia. 47.379","Baquar, S. R. & Olusi, O. O. (1988) Cytomorphological and phylogenetic studies of the genus Amaranthus from Nigeria. Kromosomo 51 - 52: 1665 - 1674.","Ugborogho, R. E. & Oyelana, O. A. (1992) Meiosis, pollen morphology and perianth stomata of some taxa of Amaranthus (Amaranthaceae) in Nigeria. Feddes Repertorium 103: 363 - 373. https: // doi. org / 10.1002 / fedr. 19921030514","Martius, C. F. P. von (1814) Plantarum Horti Academici Erlangensis. Typis Hilpertianis, Erlangae, 209 pp.","Moquin-Tandon, C. H. B. A. (1849). Amaranthaceae Juss. In: Candolle A. P. De (ed.), Prodromus systematics naturalis regni vegetabilis, vol. 13, part. 2, pp. 231 - 424. Treuttel & Wurtz, Paris.","Seubert, M. (1864) Amaranthaceae Juss. In: Martius, C. F. P. (Ed.) Flora Brasiliensis, vol. 5 (1). Frid. Fleischerm, Monachii et Lipsiae, pp. 165 - 252.","Mosyakin, S. L. & Robertson, K. R. (1996) New infrageneric taxa and combinations in Amaranthus (Amaranthaceae). Annales Botanici Fennici 33: 275 - 281.","Mosyakin, S. L. & Robertson, K. R. (2003) Amaranthus L. In: Flora of North America Editorial Committee (Org) Flora of North America North of Mexico (Magnoliophyta: Caryophyllidae, part 1), vol. 4. Oxford University Press, Oxford, pp. 410 - 435.","Iamonico, D. (2014 a) Lectotypification of Linnaean names in the genus Amaranthus L. (Amaranthaceae). Taxon 63: 146 - 150. https: // doi. org / 10.12705 / 631.34","HUH Index of Botanists (2013 - onwards) Index of botanists, Harward University Herbaria & Libraries. Available from: https: // kiki. huh. harvard. edu / databases / botanist _ search. php? mode = details & id = 266 (accessed 29 march 2022)"]}

5c. Amaranthus graecizans L. subsp. thellungianus (Nevski) Gusev, Bot. Zhurn. (Moscow & Leningrad) 57(5): 462. 1972 ≡ Amaranthus thellungianus Nevski, Trudy Bot. Inst. Akad. Nauk S.S.S.R., Ser. 1, Fl. Sist. Vyssh. Rast. 4: 311. 1937 Holotype:— TURKMENISTAN, In angustiis Bulak-Dara ad pedem montium Kuhitang supra pagum Karluk, 11 August 1931, Nevski 730 [LE non vidi fide Townsend (1985); photo of the isotype at K000814926!, image of the photo of the isotype available at http://apps. kew.org/herbcat/getImage.do?imageBarcode=K000814926). Chromosome number: —Not still counted. Occurrence in Saudi Arabia:— Chaudhary (1998: 238) indicated this taxon as “probably doubtful” in Saudi Arabia. No finding was done during the filed surveys. Further researches are necessary to verify the occurrence of this taxon in the country., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on page 143, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Townsend, C. C. (1985) Amaranthaceae. In: Polhill, R. M. (Ed.) Flora of Tropical East Africa. A. A. Balkema, Rotterdam, pp. 1 - 136.","Chaudhary, S. A. (1998) Flora of the Kingdom of the Saudi Arabia, vol. 1. Ministry of Agriculture & Water, Riyadh, 692 pp."]}

2. Amaranthus blitum L., Sp. Pl. 2: 990. 1753 Type (lectotype designated by Filias et al. 1980: 149–150):—EUROPE. Habitat in Europa temparatiore, Herb. Linn. No. 1117.14 (LINN!, image of the lectotype available at http://linnean-online.org/11640/). = Amaranthus lividus L., Sp. Pl. 2: 990. 1753, nom. rejec. (see Filias et al. 1980: 149–150) ≡ Amaranthus lividus proles lividus (Loisel.) Thell. in Asch. & Graebn. Syn. Mitteleur. Fl. [Ascherson & Graebner] 5: 274. 1914. Type (lectotype designated by Reveal & Jarvis, 2009: 978):—[Icon] “ Blitum pulchrum rectum magnum rubrum ” in Bauhin & Cherler (1651: 966); image of the lectotype available at https://www.biodiversitylibrary.org/item/246944#page/1004/mode/1up. = Amaranthus ascendens Loisel., Not. Fl. France 141. 1810 ≡ Amaranthus blitum var. ascendens (Loisel.) DC., Cat. Pl. Horti Monsp. 4. 1813 ≡ Amaranthus lividus proles ascendens (Loisel.) Thell. in Asch. & Graebn. Syn. Mitteleur. Fl. [Ascherson & Graebner]. 5(1(5)): 321 (v-322). 1914 ≡ Amaranthus lividus subsp. ascendens (Loisel.) Heukels, Geïllustreerde Schoolflora voor Nederland: 169. 1934. Type (neotype designated by Iamonico 2016a: 520):—[Icon] “ Blitum majus “ from Dodoens (1616: 617); image of the lectotype available at https://bibdigital.rjb.csic.es/viewer/11145/?offset=#page=633&viewer=picture&o=bookmark&n=0&q=. Description:— Herbs 1–5 (rarely up to 10) dm tall, monoecious, annual (therophyte). Stems prostrate-ascending, glabrous, pale green to pale brown, branched. Leaves green or green-yellowhish, ovate, rhomboidal to deltoid, some subcircular [1.5–3.5(–7.5) × (0.7–)1.5–2.5(–5.0) cm], sometimes fleshy, with entire or undulate margins, apex acute or rounded, often mucronate, base cuneate, glabrous, with marginal white vein, petioled (petiole 1.0– 5.5 cm long). Synflorescences arranged in axillary glomerules, reddish or green. Floral bracts, green or greenish, ovate to lanceolate (1.3–3.0 × 0.4–0.7 mm), shorter than the longest perianth segments, acute, margin entire, glabrous. Staminate flowers with 3(–4) tepals, ovate to lanceolate; stamens 3. Pistillate flowers with (4–)5 unequal tepals, lanceolate, elliptic [the greater 1.5–2.5(–3.5) × (0.7–)1.0– 1.2 mm], with acute to acuminate, and mucronate apex; stigmas 3. Fruit brown or reddish, ellipsoidal (2.0–2.2 × 1.0– 1.4 mm), as long as or longer than the tepals, usually smooth, dehiscent. Seed lenticular (1.5–1.7 mm in diameter), black. Taxonomic annotations:— Amaranthus blitum shows a high phenotypic variability (both in vegetative and in generative characters) and several names (at subspecies, variety, and form ranks) were published in the past, especially in the nineteenth century (see e.g., IPNI 2008). As a consequence, misapplication of names and nomenlcatural disorder exsist. We here recognized two varieties which can be distinguished as follows: 1. Seed with minutely punctiform surface and diameter 1.1–1.2 mm..................................................................................... var. blitum - Seed with smooth surface and diameter (1.2–)1.4–1.7(–1.9) mm................................................................................. var. oleraceus, Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on pages 138-139, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Filias, F., Gaulliez, R. & Guedes, M. (1980) Amaranthus blitum vs. A. lividus (Amaranthaceae). Taxon 29: 149 - 150. https: // doi. org / 10.2307 / 1219612","Bauhin, J. & Cherler J. H. (1651) Historia Plantarum Universalis, vol. 2. Fr. Lud. Graffenried, Ebroduni, 1074 pp.","Iamonico, D. (2016 a) Nomenclature survey of the genus AMARANTHUS (AMARANTHACEAE). 3. Names linked to the Italian flora. Plant Biosystems 150 (3): 519 - 531. https: // dx. doi. org / 10.1080 / 11263504.2014.987188","Dodoens, R. (1616) Stirpium Historiae pemptades sex, sive libri XXX. Ex Officina Plantiniana, Antuerpiae, 872 pp.","IPNI (2008) The International Plant Names Index. Available from: http: // www. ipni. org (accessed 29 march 2022)"]}

7b. Amaranthus blitoides var. nanus (Moq.) Iamonico, comb. nov. ≡ Amaranthus blitum var. nanus Moq., Prodr. [A. P. de Candolle] 13(2): 263. 1849 Type (lectotype designated by Iamonico 2016c: 91):— SAUDI ARABIA. Ad cisternas Dschedda Arab feliz, 02 January 1836, Schimper 857 (MPU022388!, image of the lectotype available at https://herbier.umontpellier.fr/zoomify/zoomify.php?fichier=MPU022388); isolectotypes at HAL0140219 (image of the isolectotype available at http://141.48.4.202/djatoka/jacq-viewer/viewer.html?rft_ id=hal_0140219&identifiers=hal_0140219), M0241403! (image at https://plants.jstor.org/stable/viewer/10.5555/al.ap.specimen. m0241403?loggedin=true) and M0241404! (image at https://plants.jstor.org/stable/viewer/10.5555/al.ap.specimen.m0241404). Description:— Similar to var. blitoides but smaller, i.e. 2.0– 4.5 cm tall. Phenology:— Flowering time january. Habitat and elevation:— Human-made habitat, around the sea level. Chromosome number:— Not still counted. Alien status:— Native (endemic?) to Saudi Arabia. Occurrence in Saudi Arabia (Fig. 9):— This species was firstly published for Saudi Arabia by Iamonico (2016c: 91–92; see below “TAXONOMIC NOTES”), sub Amaranthus blitum var. nanus Moq. on the basis of an old Schimper’s collection in Makkah (lectotype). No further finding was done during the filed surveys. Taxonomic notes:— Iamonico (2016c: 91) lectotypified the name Amaranthus blitum var. nanus on a specimens preserved at MPU (barcode MPU022388). We found further three specimens at HAL (barcode HAL0140219) and M (barcodes M0241403 and M0241404) which can be considered as the isolectotypes, here published for the first time. Concerrning the identity of Amaranthus blitum var. nanus, Iamonico (2016c: 91–92) proposed to synonymized it with A. blitoides based on characters of flowers. However, no discussion was provided by Iamonico (2016c: 91–92) regarding the generative characters. Based on the examination of the types of A. blitum var. nanus, and the comparison with specimens and living plants examined by one of us (DI) during the last 15 years, Moquin-Tandon’s variety appear to be very small, i.e. 2.0– 4.5 cm tall, whereas A. blitoides s.str. is at least 10–20 cm tall (see also Akeroyd 1993, Bao et al. 2003, Mosyakin & Robertson 2003, Bayón 2015, Iamonico 2015, Atlas of Living Australia 2022). Waiting further studies (floristic and molecular ones could be useful), we think that this taxon should be maintained as separate for the moment, at least at variety rank. Lacking a combination under A. blitoides, we here propose a nomenclatural change. Specimina visa selecta:— SAUDI ARABIA, Makkah, Ad cisternas Dschedda Arab feliz, 02 January 1836, Schimper 857 (MPU022388!), Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on page 147, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Iamonico, D. (2016 c) Nomenclature survey of the genus Amaranthus (Amaranthaceae). 5. Moquin-Tandon's names. Phytotaxa 273 (2): 81 - 114. https: // doi. org / 10.11646 / phytotaxa. 273.2.1","Akeroyd, J. R. (1993) Amaranthus L. In: Tutin, T. G., Burges, N. A., Chater, A. O., Edmondson, J. R., Heywood, V. H., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A. (Eds.) Flora Europaea (second edition), vol. 1. Cambridge University Press, Cambridge, pp. 130 - 132.","Bao, B., Clemants, S. E. & Borsch, T. (2003) Amaranthus L. In: Wu, Z. Y., Raven, P. H. & Hong, D. Y. (Eds.) Flora of China, vol. 5. Science Press, Beijing and Missouri Botanical Garden Press, St. Louis, pp. 415 - 429.","Mosyakin, S. L. & Robertson, K. R. (2003) Amaranthus L. In: Flora of North America Editorial Committee (Org) Flora of North America North of Mexico (Magnoliophyta: Caryophyllidae, part 1), vol. 4. Oxford University Press, Oxford, pp. 410 - 435.","Bayon, N. D. (2015) Revision taxonomica de las especies monoicas de Amaranthus (Amaranthaceae): Amaranthus subg. Amaranthus and Amaranthus subg. Albersia. Ann. Missouri Bot. Garden 101 (2): 261 - 383. https: // doi. org / 10.3417 / 2010080","Atlas of Living Australia (2022) Amaranthus blitoides S. Watson. Available from: https: // bie. ala. org. au / species / NZOR- 6 - 118464 (accessed 19 January 2022)"]}

6. Amaranthus sparganicephalus Thell. in Ascherson & Graebner, Syn. Mitteleur. Fl. 5: 312. 1914 Type (neotype, here designated):— OMAN, Dhofar, J. Qara, nr. Aqarnahawat, Acacia hollow, 880 m a.s.l., 19.09.1985, A. G. Miller 7693 (E00687024!, image of the neotype available at https://data.rbge.org.uk/herb/E00687024). Description:— Herbs, 0.7–6 cm tall, monoecious, annual (therophyte). Stems erect, glabrous (pubescent in the upper part), yellowish, simple or branched (branches sometimes decumbent). Leaves green to dark-green, ovate (1.5–5.5 × 0.6–3.0 cm), with entire margins, apex obtuse to retuse, mucronate, base cuneate, glabrous (short hairs on the nerves of the abaxial surface), long petioled (petiole up to 6.0 cm long). Synflorescences arranged in axillary spherical glomerules, ± 1 cm in diameter, brown to dark-brown. Floral bracts ovate (0.3–0.5 × ca. 0.2 cm), about 1/2 times shorter than the perianth, acute to acuminate, mucronate. Staminate flowers with 3 tepals, green, ovate-lanceolate; stamens 3. Pistillate flowers with 3 tepals, green, ovate-lanceolate (1.0–1.3 × ca. 0.3 mm), with obtuse apex, median vein green; stigmas 2. Fruits arranged in stellate heads (divergent capsules), each one brown, as a double cone (2.75–3.25 × ca. 1.5 mm), longer than the perianth, the half base longitudinally sulcate, dehiscent with point of junction of lid and base cristate-crenulate. Seeds lenticular (1.2–1.5 mm in diameter), black. Iconography:— Townsend (1985: 33, Fig. 6). Phenology:— Flowering time from march to april. Habitat and elevation:— Uncultivated land, around 2000 m a.s.l. Chromosome number:— Not still counted. Chorology:— Species native to eastern tropical Africa (Djibouti, Eritrea, Ethiopia, Kenya, Somalia, Sudan, Tanzania), Arabian Peninsula (Saudi Arabia, Yemen, Oman), and Socotra (POWO 2022b and literature therein). Occurrence in Saudi Arabia (Fig. 6): — Riyadh. Typification of the name Amaranthus sprganicephalus:— Amaranthus sparganicephalus was validly published by Thellung (1914: 312, a note) by a short diagnosis (in german) in which the following two characters were highlighted: the shape of the fruiting glomerules (which resembles those of the members belonging to the genus Sparganium L.; the specific epithet “ sparganicephalus ” derives from this feature) and that of each fruit (“polyedrisch abgeflachten” = “polyhedral flattened”); a morphologic comparison with A. angustifolius Lam. (currently A. graecizans subsp. graecizans) and A. macrocarpus Benth. was also given. Finally the provenance (“tropischen Africa... und Arabiens” = tropical Africa and Saudi Arabia) and three specimens (“ Abessinien: Massaua: Hildebrandt n. 716!; ostafrican. Grabenrand, 1904, Merken!... “Chedrasch et Chedolia, Ehrenberg!”) were reported. According to the Art. 9.6 of ICN, these three citations are syntypes, original material for the name A. sparganicephalus (Art. 9.4 of ICN), and useful for the lectotypification purpose (Art. 9.3 of ICN). Verdcourt (1967: 252) listed 16 specimens of Amaranthus sparganicephalus adding “ syntype ” after three of them, i.e. “ARABIA. Chedrasch and Chedolia, Ehrennberg (B)”, “ ERITREA. Massawa, Hildebrandt 716 (B)”, and “ TANZANIA. Grabenland, 1904, Merker (B)”. These three specimens was also cited (as “Types”) by Townsend (1985: 32) in his treatment of Amaranthaceae for the Flora of Tropical East Africa. According to Shenzen Code, neither Verdcourt (1967: 252) nor Townsend (1985: 32) proposed a correct typification, since they just re-listed the syntypes which was originally reported by Thellung (1914: 312) in the protologue. As a consequence, a lectoptypification is necessary. Note moreover that both Verdecourt and Townsend reported after the syntypes the symbol “†” which would indicate that the specimen was are no longer exsisting. R. Vogt (pers. comm.) informed one of us (DI) that no original material for A. sparganicephalus is preserved at B being probably lost/destroyed during the II World War. Lacking material useful for the lectotypification purpose (Arts. 9.3 and 9.4 of ICN), a neotyipfication is required under the Art. 9.8 of ICN. We here propose to designate, as neotype of the name A. sparganicephalus, a well preserved specimen at E (barcode E00687024) collected in Oman in 1985 which matches the Thellung’s description and the current application of the name (see e.g., Townsend 1985: 32). Specimina visa selecta:— SAUDI ARABIA. Raidah Village near base of scarp. 25 km NNW of Abha, waste ground in villane, 07 April 1995, Collinette 9337 (E00121397!)., Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on pages 144-145, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Townsend, C. C. (1985) Amaranthaceae. In: Polhill, R. M. (Ed.) Flora of Tropical East Africa. A. A. Balkema, Rotterdam, pp. 1 - 136.","POWO (2022 b) Plants of the World Online. Amaranthus sparaganicephalus Thell. Available from: https: // powo. science. kew. org / taxon / urn: lsid: ipni. org: names: 59735 - 1 (accessed 29 March 2022)","Thellung, A. (1914) Amaranthus L. In: Ascherson, P. & Graebner, P. (Eds.) Synopsis der Mitteleuropaischen Flora, vol. 5. Verlag Von Gebruder Borntraeger. Leipzig, Germany, pp. 225 - 356.","Verdcourt, B. (1967) Tropical African Plants: XXVIII. AMARANTHACEAE. Amaranthus sparganiocephalus. Kew Bulletin 21 (2): 252. https: // doi. org / 10.2307 / 4108530"]}

5. Amaranthus graecizans L., Sp. Pl. 2: 990. 1753 Type (lectotype designated by Fernald 1945: 139):— U.S.A. Habitat in Virginia, Herb. Clayton No. 442 (BM000051563!, image of the lectotype available at https://data.nhm.ac.uk/object/ca635ca9-9252-42a3-9082-60ec097bc2d6/1641427200000). = Amaranthus angustifolius Lam., Encycl. [J. Lamarck & al.] 1: 115. 1783, nom. illeg. Art. 52.21 of the ICN (Turland et al. 2018). 1 Amaranthus angustifolius was described citing among synonyms an earlier legitimate name (A. graecizans L.). Description:— Herbs 1–8 dm tall, monoecious, annual (therophyte). Stems erect or ascending, ± glabrous (sometimes sparsely pubescent in the distal region), pale to black-brown to reddish, usually branched. Leaves usually green, ovaterhomboidal to lanceolate (decreasing in size towards stem apex), with entire margins, apex acute or obtuse, sometimes mucronate, base cuneate, glabrous, petioled [petiole (1.0–)2.0–5.0(–6.0) cm long]. Synflorescences arranged in axillary glomerules, often reddish. Floral bracts brown-yellowish, lanceolate (1.2–2.0 × 0.3–0.6 mm) as long as or shorter than the perianth, acute, margin entire, glabrous. Staminate flowers with 3 tepals, ovate to lanceolate; stamens 3. Pistillate flowers with 3 tepals, ovate-lanceolate [(1.3–)1.5–2.0 × 0.4–0.7 mm], with acute, and often mucronate apex; stigmas 3. Fruit brown, subglobose [(1.5–)2.0–2.5(–2.7) × (1.0–)1.4–1.5(–1.8) mm], longer than the perianth, rugose, dehiscent. Seed lenticular [1.0–1.3(–1.5) mm in diameter], black to dark-brown. Chorology:— Paleotemperate taxon native to Europe, Central-Western Asia, and Northern Africa (Carretero 1990, Akeroyd 1993, Boulos 1999, Ghafoor et al. 1977, Fennane & Tatou 2005, Le Floc’h et al. 2008), it is considered introduced in some European countries, North America, South Africa, and Australia (POWO 2022a and literature therein). Concerning Saudi Arabia, it is native. At subspecific rank two main distribution areas can be distinguished, the first one including Central and southern Europe plus North Africa [subsp. graecizans and subsp. sylvestris (Vill.) Brenan], the second area being the eastern Europe (Russia and adjacent territories) plus Central and southern Asia [subsp. aschersonianus (Thell.) Costea and subsp. thellungianus (Nevski) Gusev] (see Iamonico 2015: 34). Occurrence in Saudi Arabia:— See varieties. Taxonomic annotations:— Amaranthus graecizans is a species morphologically variable, especially regarding the hairiness of stem, the shape of leaves (lanceolate or ovate-rhomboidal), the structure of synflorescence (with or without terminal synflorescence), the apex of bracts and tepals (acute-mucronate or awned), the margin of seed (obtuse or acute), and the dehiscence/indehiscence of fruit. These variability is currently interpreted recognizing four subspecies, i.e. subsp. graecizans, subsp. sylvestris, subsp. aschersonianus, subsp. thellungianus (see e.g., Costea 2003). Based on our field surveys and according to Chaudhary (1998) three subspecies occur in Saudi Arabia. These taxa can be distinguisced as follow: 1. Bracts and tepals awned (awn 0.3–0.7 mm long)................................................................................................ subsp. thellungianus 2. Bracts and tepals mucronate (mucro about 0.1 mm long)..................................................................................................................3 3. Leaf blade lanceolate [2.0–3.0(–4.0) × 0.5–1.0 cm], ratio length/width of the blade 3.0–6.0................................ subsp. graecizans - Leaf blade ovate-rhomboidal [5.0–6.0 × 2.5–3.0(–3.5) cm], ratio length/width of the blade 1.8–2.2....................... subsp. sylvestris, Published as part of Hassan, Walaa A., Al-Shaye, Najla A., Alghamdi, Salma, Korany, Shereen M. & Iamonico, Duilio, 2022, Taxonomic revision of the genus Amaranthus (Amaranthaceae) in Saudi Arabia, pp. 135-157 in Phytotaxa 576 (2) on pages 141-142, DOI: 10.11646/phytotaxa.576.2.1, http://zenodo.org/record/7461280, {"references":["Fernald, M. L. (1945) Botanical specialities of the Seward Forest and adjacent Areas of Southeastern Virginia. Rhodora 47: 93 - 142.","Turland, N. J., Wiersema, J. H., Barrie, F. R., Greuter, W., Hawksworth, D. L., Herendeen, P. S., Knapp, S., Kusber, W. - H., Li, D. - Z., Marhold, K., May, T. W., McNeill, J., Monro, A. M., Prado, J., Price, M. J. & Smith, G. F. (2018) International Code of Nomenclature for algae, fungi, and plants (Shenzhen Code) adopted by the Nineteenth International Botanical Congress, Shenzhen, China, July 2017. Regnum Vegetabile 159: i - xxxviii + 1 - 254. https: // doi. org / 10.12705 / Code. 2018","Carretero J. L. (1990) Amaranthus L. In: Castroviejo, S., Lainz, M., Lopez Gonzales, G., Montserrat, P., Munoz Garmendia, F., Paiva, J. & Villar, L. (Eds.) Flora Iberica, vol. 2. Real Jardin Botanico, CSIC, Madrid, pp. 559 - 569.","Akeroyd, J. R. (1993) Amaranthus L. In: Tutin, T. G., Burges, N. A., Chater, A. O., Edmondson, J. R., Heywood, V. H., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A. (Eds.) Flora Europaea (second edition), vol. 1. Cambridge University Press, Cambridge, pp. 130 - 132.","Ghafoor, A., Jafri, S. M. H. & El-Gadi, A. (1977) Amaranthaceae. In: Jafri, S. M. H. & El-Gadi, A. (Eds.) Flora of Libya, vol. 42. Al Faateh University, Tripoli, pp. 1 - 25.","Fennane, M. & Tatou, M. (2005) Flore Vasculaire du Maroc. Inventaire et chorologie. Travaux de l'Institut Scientifique, Universite Mohammed V. Serie Botanique 37: 1 - 483.","POWO (2022 a) Plants of the World Online. Amaranthus graecizans L. Available from: https: // powo. science. kew. org / taxon / urn: lsid: ipni. org: names: 10641 - 2 (accessed 29 march 2022)","Costea, M. (2003) The identity of a cultivated Amaranthus from Asia and a new nomenclature combination. Economic Botany 57: 646 - 649. https: // doi. org / 10.1663 / 0013 - 0001 (2003) 057 [0646: NOEP] 2.0. CO; 2","Chaudhary, S. A. (1998) Flora of the Kingdom of the Saudi Arabia, vol. 1. Ministry of Agriculture & Water, Riyadh, 692 pp."]}