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Stipa baxoiensis Y. Zhang & W. L. Chen, sp. nov. (Figs. 1, 2) Type:— CHINA. Tibet: Baxoi County, Bangda town, Ye-la Mountain, 30.13°N, 97.277°E, in shrubs on rocky slopes, alt. 4238 m, 15 July 2022, C. Zhang 3 (holotype: PE, No. 2714338; isotypes: PE, No. 2714339, No. 2714340, No. 2714341). Diagnosis:— Stipa baxoiensis is close to S. subsessiliflora (Ruprecht 1869: 35) Roshevitz (1915: 50) in the contracted and suberect panicles, but differs mainly by its densely hirsutulous leaf sheath and adaxial surface of leaf blade, and the scabrous middle awn segment. Description:— Perennial, densely tufted, intravaginal, not rhizomatous. Culms 20–45 cm tall, erect, glabrous, 1–2-noded. Sheaths of basal leaves 5–7 cm, sheaths of cauline leaves 10–15 cm, longer than internodes, both densely hirsutulous. Basal ligules 1.5–2 mm, membranous, lanceolate, apex acuminate, margin ciliate, with dense pubescence dorsally, ca. 0.1 mm; cauline ligules 1–1.5 mm, slightly shorter than those of basal leaves, apex obtuse, margin ciliate. Blades of basal leaves 2–15 cm, blades of cauline leaves 4–7 cm, both convolute, ca. 1 mm in diam., densely hirsutulous on both surfaces, hairs ca. 0.2 mm and ca. 0.1 mm long on abaxial and adaxial surface respectively. Panicles contracted, 8–15 cm long, 1–1.5 cm wide, exserted from uppermost leaf sheaths; branches straight, with 5–10 spikelets. Spikelets yellowish green; lower glume 7–9 mm, much longer than floret, lanceolate, 5–veined, apex acuminate; upper glume 6–9 mm, equal or slightly shorter than lower glume; lemma 5–7 mm, terete, pilose on abaxial surface, with overlapping margins; callus ca. 1 mm, pungent; awn 15–22 mm, with joint at the base, 2-geniculate, lower awn segment 5–6 mm, with 1.5–2 mm long hairs, middle awn segment 3–4 mm, scabrous, bristle 8–10 mm, straight, glabrous or slightly scabrous; palea 5–7 mm, subequal to lemma, membranous, 2-veined, usually hairy between veins; lodicules 3, lanceolate, membranous, 1.5–2 mm; anthers 3, dark purple, 3–4 mm, glabrous at apex; styles 2. Distribution and habitat:— Stipa baxoiensis is distributed in Bangda town, Baxoi County, Qamdo city, Tibet. The new species is currently known only from the eastern QTP, near the Nujiang River Basin, and grows in shrubs on rocky slopes at elevations from 4200–4400 m above sea level (Fig 2: B). Phenology:— Flowering and fruiting from July to October. Etymology:— The specific epithet refers to the type locality, Baxoi county (E QTP, China). Additional specimens examined: — CHINA. Tibet: Baxoi County, Bangda town, Ye-la Mountain, 30.143°N, 97.2881°E, in shrubs on rocky slopes, alt. 4403 m, 6 September 2021, X. Y. Zhang & W. H. Li 440 (PE, No. 2641506). Taxonomic notes:— Tzvelev (1974, 1976, 1993) recognized nine sections of Stipa from the Soviet Union mainly based on the characteristics of glumes, lemmas, awns and ligules. Emphasizing the awn characteristics, Kuo (1982) divided Chinese Stipa into five sections. He combined sect. Pseudoptilagrostis Tzvelev (1974: 13) with sect. Regelia based on the character combination of awn 2–3 cm long, 2-geniculate, and column plumose and included five species and two varieties in the section. Recently, Nobis et al. (2015, 2016) accepted two varieties of Stipa aliena Keng (1941: 74), and published a new species Stipa dickorei. Up to now, a total of seven species and four varieties was included in section Regelia mainly distributed in western China: S. regeliana Hackel (1884: 130), S. dickorei, S. basiplumosa Munro ex Hooker (1896: 229), S. subsessiliflora, S. baxoiensis, S. aliena var. aliena, S. aliena var. macrocarpa (Martinovský 1970: 163) Nobis (2015: 238), S. penicillata Handel-Mazzetti (1936: 226) var. penicillata and S. penicillata var. hirsuta P. C. Kuo & Y. H. Sun (1984: 89) (Kuo & Sun 1982, Nobis et al. 2015, Nobis et al. 2016). The new species Stipa baxoiensis belongs to sect. Regelia due to its 2-geniculate awns, plumose columns and glabrous bristles (Kuo & Sun 1982). It is similar to S. subsessiliflora in contracted panicles but differs in the hirsutulous (vs. glabrous) leaf sheath and abaxial surface of leaf blades, glumes 7–9 mm (vs. 6–8. 5 mm) long, the middle awn segment scabrous (vs. with 1–1.5 mm long hairs), and panicles exserted from uppermost leaf sheaths (vs. enclosed by uppermost leaf sheaths at base) (Fig 2: C–E). In sect. Regelia, both the new species and S. penicillata var. hirsuta have much hairy leaf sheaths and blades, but the later differs by its lax panicles, panicle branches flexuous and with cushions in axils, and longer hairs on middle awn segment (Fig 2: C–E). A detailed comparison among the new species and all the other members of the sect. Regelia in China is given in Table 1 as well. The morphological character of densely haired leaves is seldom happened in Stipa and possibly an adaptation strategy to the cold or arid environment at QTP (Fig 2: B). Stipa zhadaensis and S. arabica Trinius & Ruprecht (1842: 77) var. turgaica (Roshevitz 1949: 21) Tzvelev (1976: 584) are another two taxa from QTP with much haired leaves, but they are members of the section Barbatae Junge (1910: 130), with awns plumose throughout their length (Kuo & Sun 1982)., Published as part of Zhang, Yue, Zhang, Xie-Yong, Zhang, Chao, Chen, Wen-Li & Zhu, Shi-Xin, 2023, Stipa baxoiensis (Stipeae, Poaceae), a new species from Qinghai-Tibet Plateau, China, pp. 280-286 in Phytotaxa 597 (4) on pages 281-284, DOI: 10.11646/phytotaxa.597.4.3, http://zenodo.org/record/7958624, {"references":["Ruprecht, F. J. (1869) Sertum Tianschanicum. In: Osten-Sacken, F. von & Ruprecht, F. J. (Eds.) Sertum Tianschanicum, Botanische Ergebnisse einer Reise im mittleren Tian-Schan. Memoires de l'Academie Imperiale des Sciences de Saint-Petersbourg 14 (4): 33 - 74.","Roshevitz, R. Y. (1915) Stipa L. In: Fedchenko, B. A. (Ed.) Spisok ruskikh rastenii. [Suppl. 2] Izvestiya Imperatorskogo Botanicheskogo Sada Petra Velikago 14: 48 - 50.","Tzvelev, N. N. (1974) Zametki o tribe Stipae Dum. semejstva zlakov (Poaceae) v SSSR - Notulae de tribu Stipae Dum. (fam. Poaceae) in URSS. Novosti Sistematiki Vysshikh Rastenii 11: 4 - 21.","Tzvelev, N. N. (1976) Zlaki SSSR. Nauka, Leningrad, 788 pp.","Tzvelev, N. N. (1993) Some notes on the grasses (Poaceae) of the Caucasus. Botanicheskii Zhurnal 78: 83 - 95.","Kuo, P. C. & Sun, Y. H. (1982) A preliminary study on the classification, distribution and ecological nature of genus Stipa L. of China. Acta Phytotaxonomica Sinica 20: 34 - 44.","Nobis, M., Nowak, A. & Gudkova, P. D. (2015) A new synonym and a new combination in Stipa aliena Keng (Poaceae: Stipa sect. Regelia). Phytotaxa 195: 236 - 242. http: // dx. doi. org / 10.11646 / phytotaxa. 195.3.3","Nobis, M., Nobis, A., Klichowska, E., Nowak, A., Nowak, S. & Gudkova, P. D. (2016) Stipa dickorei sp. nov. (Poaceae), three new records and a checklist of feather grasses of China. Phytotaxa 267: 29 - 39. http: // dx. doi. org / 10.11646 / phytotaxa. 267.1.3","Keng, Y. L. (1941) An enumeration of grasses of Kansu Province. Sunyatsenia 6 (1): 52 - 76.","Hackel, E. (1884) Gramina nova vel minus nota. Sitzungsberichte der Mathematisch-Naturwissenschaftlichen Classe der Kaiserlichen Akademie der Wissenschaften 89: 123 - 136.","Hooker, J. D. (1896) Flora of British India, 7. L. Reeve & Co., London, 842 pp. https: // doi. org / 10.5962 / bhl. title. 678","Martinovsky, J. O. (1970) Stipa smithii Martinovsky, eine neue Chinesische Federgrasart. XX. Beitrag zur Kenntnis der Federgrassippen. Svensk Botanisk Tidskrift 64 (2): 158 - 164.","Handel-Mazzetti, H. (1936) Kleine Beitrage zur Kenntnis der Flora von China. Oesterreichische Botanische Zeitschrift 85: 226 - 227. http: // dx. doi. org / 10.1007 / BF 01255464","Trinius, C. B. & Ruprecht, F. J. (1842) Species Graminum Stipaceorum. Typis Academiae Imperialis Scientiarum, Petropoli, 189 pp. http: // dx. doi. org / 10.5962 / bhl. title. 15631","Roshevitz, R. Y. (1949) Gramineae novae, V. Botanicheskie Materialy Gerbariya Botanicheskogo Instituta im. Komarova AN SSSR 11: 18 - 31.","Junge, A. E. (1910) Dva novykh kovylya iz Turkestana. Stipa magnifica mihi sp. nova i Stipa lingua mihi sp. nova. Izvestija Imperatorskago S. - Peterburgskago Botanicheskago Sada 10: 124 - 130."]}

Key to the species of Stipa sect. Regalia in China 1. Panicles contracted and panicle branches straight..............................................................................................................................2 - Panicles lax and panicle branches flexuous........................................................................................................................................6 2. Awn column with hairs up to 1 mm long...........................................................................................................................................3 - Awn column with hairs 1.5–4 mm long.............................................................................................................................................4 3. Ligules of basal leaves 4–6 mm, leaf blades scabrous..................................................................................................... S. regeliana - Ligules of basal leaves 0.3–1.6 mm, leaf blades glabrous.................................................................................................. S. dickorei 4. Glumes 9.5–13.5 mm, with 2–3 mm long-pointed; awn 1.5–1.8(1.9) cm.................................................................. S. basiplumosa - Glumes 6–9 mm; awn (2.1) 2.2–2.7 cm..............................................................................................................................................5 5. Base of panicles enclosed by uppermost leaf sheaths; leaf sheaths and adaxial surface of blades glabrous or scabrous....................................................................................................................................................................................................... S. subsessiliflora - Panicles exserted from uppermost leaf sheaths; leaf sheaths and adaxial surface of blades hirsutulous........................ S. baxoiensis 6. Adaxial surface of leaf blades smooth, glabrous; panicle branches ascending, without cushion in axils..........................................7 - Adaxial surface of leaf blades scabrid or hairy; panicle branches spreading, with cushion in axils..................................................8 7. Lemma 6.3–8.5 mm long, awn 15–26 mm long................................................................................................... S. aliena var. aliena - Lemma 9–12 mm long, awn 23–30 mm long............................................................................................. S. aliena var. macrocarpa 8. Leaf sheaths and adaxial surface of leaf blades scabrous....................................................................... S. penicillata var. penicillata - Leaf sheaths and adaxial surface of leaf blades hirsute............................................................................... S. penicillata var. hirsuta, Published as part of Zhang, Yue, Zhang, Xie-Yong, Zhang, Chao, Chen, Wen-Li & Zhu, Shi-Xin, 2023, Stipa baxoiensis (Stipeae, Poaceae), a new species from Qinghai-Tibet Plateau, China, pp. 280-286 in Phytotaxa 597 (4) on pages 284-285, DOI: 10.11646/phytotaxa.597.4.3, http://zenodo.org/record/7958624