Homostylium cabulicum (Lindl.) Nees.

Perennial shrubs. Stems erect to spreading, profusely branched. Leaves alternate, leathery, subleathery, herbaceous, or chartaceous, basal leaves withering at flowering, middle cauline leaves ovate, lanceolate to linear; margins entire to remotely apiculate, serrulate, or coarsely serrate, revolute or flat; adaxially glabrous or sparsely appressed pubescent; abaxially closely gray- to white-tomentose or sometimes glabrous, sometimes glandular beneath the tomentum with sessile, resinous glands. Capitula pedunculate, solitary or in corymbose or paniculate-corymbose inflorescences at branch tips. Involucres campanulate, cylindrical or obconic, 5–9 mm wide (pressed). Phyllaries in 3–5-seriate, imbricate, strongly graduate, keeled, oblong, ovate, ovate-lanceolate to lanceolate, glabrous to nearly glabrous, or sparsely short pubescence, tomentum; margins membranaceous or scarious, sometimes ciliate, abaxially herbaceous or sometimes leathery. Florets heteromorphic, numerous, outer ray florets 1-seriate, pistillate, white, pink, or violet-blue, lamina 3-lobed, glabrous, glabrescent, sparsely filiform-pilose or puberulent; central disc florets numerous, bisexual, yellow, tubes glabrous or sparsely to moderately pilosulous basally or apically, limb 5- lobed, lobes equal or unequal, glabrous or sparsely puberulent, sometimes glandular. Anthers linear, base obtuse, subauriculate, or caudate, apical appendage lanceolate. Styles glabrous or distally papillate; bifid in disc florets, branches linear, abaxially glabrous or sparsely papillate, adaxially two stigmatic lines of densely papillate cells from base to appendages; apical sterile appendages triangular or lanceolate, papillate; filiform in ray florets, not bifid. Receptacles flat or convex to conic, alveolate, sometimes lacerate, epaleate, glabrous. Pappus persistent, white, straw-colored, or reddish-brown, with numerous subequal strigose bristles, outer layer extremely short strigose bristles. Achenes white, straw-colored, tan, or reddish brown, compressed, fusiform, cylindrical, oblong, or obovoid, strigillose, (3-)5–8-ribbed, pilose, pubescent, or glandular-pubescent.

6 of 7 species endemic to SW China. Only Homostylium albescens distributed widely in SW China and the Himalayan region (Nepal, Bhutan, India, Myanmar, Bangladesh, and Kashmir) (Fig. 1).

Figure 1. 

Distribution of the genus Homostylium Nees. China is centrally located on the map.

Alpine and subalpine forests and shrubs, aridly hot river valleys, rock cliffs, and streambanks.

Flowering June to October. Fruiting August to November.

It is derived from the Greek “Homo-”, meaning “same”, and “-styl-”, meaning “pillar/style”, combined with the Latin “-ium”, a common neuter genus suffix. The genus name probably refers to the uniform style in the florets of Homostylium species.

Among the seven species names in Aster ser. Albescentes, the earliest published was Amphirhapis albescens DC. in 1836 by A. P. de Candolle, with no type cited. Jeffrey (1982) later typified the genus Amphirhapis DC. with Amphirhapis heterotricha DC. However, this species was subsequently treated as a synonym of Duhaldea eupatorioides (DC.) Steetz in the genus Duhaldea DC. of the tribe Inuleae (Anderberg 1991). It made the name Amphirhapis no longer applicable to accommodate Aster ser. Albescentes. The second earliest name was Homostylium Nees published in 1844 by Mr. C. G. D. Nees von Esenbeck. Homostylium was originally a monotypic genus including only Homostylium cabulicum (Lindl.) Nees. This species is currently treated as a synonym for Aster albescens. The genus is characterized by its shrubby habit, dentate leaves, corymbose inflorescences, cylindrical involucres, imbricately arranged lanceolate-acuminate phyllaries, 1-seriate pistillate pale violet ray florets, bisexual disc florets with 5-lobed limb, and compressed, pubescent, cuneate achenes, as described in its original protologue (https://seedlists.naturalis.nl/content/homostylium-cabulicum-nees). The original morphological characters of Homostylium are generally consistent with those of Aster ser. Albescentes. However, no type specimen information was provided in the protologue.

In the Flora Reipublicae Popularis Sinicae (Ling et al. 1985), we found that Homostylium cabulicum was cited as a synonym under the name Aster albescens. However, Mr. Rong Ling marked this synonym as “nom. nud. ?”, suggesting it might be a nomen nudum with uncertainty. This was probably due to him not having seen the original literature. After reviewing the original literature published in 1844, we found the monotypic genus Homostylium had a detailed description of its characteristics and essential traits, confirming it as validly published and not a nomen nudum. Notably, the name Homostylium has not also been used for other taxa. Therefore, we adopted the validly published genus name Homostylium with nomenclatural priority to accommodate 7 species of Aster ser. Albescentes, in accordance with Articles 11, 41.2, and 42.1 of International Code of Nomenclature for Algae, Fungi, and Plants (Shenzhen Code) (Turland et al. 2018). Initially, Homostylium was published as applicable only to Aster albescens. However, to include the remaining six species (A. lavandulifolius, A. argyropholis, A. fulgidulus, A. motuoensis, A. hypoleucus, and A. polius) and its varieties, the genus concept is broadened.

Nepal • Kamaon, Gossain-Than. N. Wallich 2974/84 (lectotype, designated by Nesom (2020g), K 001118307!) (Suppl. material 1: fig. S1).

Shrubs, 28–194 cm tall. Leaves subpapery, narrowly to broadly lanceolate, ovate, elliptic, or oblong-lanceolate, or elliptic, (2–)3–17(–21) × (0.4-)1–3(-12) cm, midvein and pinnate lateral veins abaxially prominent, veins scabrous or glandular-punctate, sparsely to moderately villosulous; margins entire or teeth mucronulate, upper leaves smaller; adaxially glabrous or scabridulous to scabrous, eglandular or rarely sparsely minutely stipitate glandular; abaxially glabrous or sparsely to densely appressed villosulous to tomentulose, eglandular or sometimes sparsely to densely minutely stipitate glandular. Capitula 6–40 (5–8 mm wide), in terminal compound corymbiform synflorescences at branch tips. Peduncles slender, 5–11 mm long, bracts subulate. Involucres obconic to campanulate, 4–7 mm long. Phyllaries 4–5 seriate, imbricate, unequal, glabrescent to pubescent or tomentose, outer series narrowly lanceolate, ca. 1 mm long, inner series linear-lanceolate, 3.5–4.8 × 0.6–0.8 mm.

Figure 2. 

Homostylium albescens (DC.) Z.X.Fu. A. Flowering plant; B. Abaxial surface of leaf. Photographed by Z. X. Fu.

Widely distributed in China (S Gansu, N Guizhou, W Hubei, S Shaanxi, Sichuan, S Xizang, N Yunnan), Himalayas region (Bhutan, N India, Kashmir, and Nepal), N Myanmar, and N Bangladesh (Fig. 3).

Figure 3. 

Distribution of Homostylium albescens. China is centrally located on the map.

Margins of deciduous or coniferous forests and thickets, open or grazed meadows, shrublands, seepage or damp areas, streamsides, ditch or field margins, disturbed areas and cut or disturbed forests, hills to alpine regions. 500–4100 m.

Flowering June to September. Fruiting August to October.

It is derived from the Latin “albesco-” meaning “to become white” and the neuter suffix “-ens”, indicating a present participle or ongoing action. The specific epithet likely refers to the gradual whitening of tomentose on the abaxial surface of the leaf in this species.

In the Flora Reipublicae Popularis Sinicae (Ling et al. 1985) and Flora of China (Chen et al. 2011), Homostylium albescens (≡ Aster albescens) was treated under the genus Aster. In both Floras, the classification of its intraspecific taxa is nearly consistent. H. albescens is a variable complex of intergrading populations of shrubs extending from the western Himalaya to central and south-central China. To facilitate taxonomic work, we have reviewed relevant literature and examined the type specimens and photos of these populations in herbarium collections. Ten varietal names (except type variety) have been assigned to segregate this complex in China, primarily based on pubescence, gland characters, size of the leaves, and pubescence and shape of the involucres (Boufford and Chen 2009). Some of these do not appear to warrant recognition yet. Certain varieties are considered to be closer to, or intermediate between other species. A molecular phylogenetic study is required to further clarify this complex. However, no effort is made herein to assess their evolutionary validity. While these varieties are not formally recognized here, they are still listed below along with their key features and comments. Our current understanding of intraspecific variation in Homostylium albescens is very limited. Additional collections from the type locality are particularly needed for future study.

Leaves narrowly to broadly lanceolate, 5–12 × 1–12.5 cm, abaxially gray-white appressed tomentulose, margin flat, entire. Phyllaries outer ovate, abaxially sparsely hairy or glabrate.

Widely distributed in China (Chongqing, Gansu, Guizhou, W Hubei, S Shaanxi, S Sichuan, E and N Xizang, and NW Yunnan), and S and W Himalayan region (Myanmar, India, Bhutan, Nepal, and Kashmir).

Understories and shrublands from low to high mountains. 400–4300 m.

China • Chongqing: Leijiaping, A. V. Rosthorn 136 (B); Chengkou, T. L. Dai 101444 (PE), 101639 (PE), 101838 (PE), 101982 (PE), 102535 (PE), 103225 (PE 00274528, PE 01831284), 103407 (PE), 103509 (PE), 103650 (PE), 103834 (PE), 103975 (PE), 104192 (PE), 104266 (PE), 104331 (PE), 104428 (PE), 105954 (PE), 106361 (PE), 107079 (PE); Fengjie, H. F. Zhou 26755 (PE), 26884 (PE 00274620, PE 00300444), T. Y. Chang 25759 (PE 00274494, PE 00300443), 25892 (PE), M. Y. Fang 23956 (PE), 24870 (PE), 24979 (PE), Anonymous 24696 (PE); Hechuan, T. H. Tu 5196 (PE); Nanchuan, K. C. Kuan et al. 1409 (PE 00274510, PE 00274511), J. H. Xiong & Z. L. Zhou 92893 (PE), 93620 (PE), G. F. Li 63361 (PE), 64223 (PE), Z. Y. Liu 17947 (PE); Wushan, K. H. Yang 59843 (PE), H. F. Zhou & H. Y. Li 110020 (PE); Wuxi, K. H. Yang 59482 (PE), 65060 (PE), 65481 (PE), K. L. Chu 1898 (PE), 1946 (PE); • Gansu: Chengxian, W. Y. Hsia 6127 (PE); Tanchang, Y. M. Yuan 1084 (PE), T. P. Wang 14307 (PE); Kangxian, Z. Y. Zhang 16747 (PE), 17238 (PE), 16429 (PE), Y. S. Lian et al. 96309 (PE); Wenxian, Z. Y. Zhang 13999 (PE), 15534 (PE), 14992 (PE), 15188 (PE), 14317 (PE), Q. X. Li & X. C. Zhao 2376 (PE), 2153 (PE); Zhouqu, Y. Q. He 544 (PE 00274485, PE 00274486); • Guizhou: Chishui, Bijie Exped. 1243 (PE); Daozhen, Z. Y. Liu 16233 (PE); Renhuai, X. L. Wang 2189 (PE); Sinan, J. Zhang 4061 (PE); Weining, Bijie Exped. 224 (PE 00274646, PE 00274647, PE 01776696); Xishui, P. C. Tsoong 292 (PE 00274641, PE 00274642, PE 00274643, PE 00274644); Bijie, Bijie Exped. 1546 (PE 00274650, PE 00274651, PE 01776697), 1618 (PE 00274648, PE 00274648, PE 01823525), 1719 (PE 00274652, PE 00274653, PE 01823526), C. W. Wu 1217 (PE); Zunyi, Sichuan–Guizhou Exped. 1055 (PE), 1411 (PE); Tien-sen-kiao river, J. Cavalerie 1895 (E); • Hubei: Lichuan, W. C. Cheng & C. T. Hwa 967 (PE), L. Y. Dai & C. H. Qian 822 (PE); Xingshan, Z. D. Chen et al. 961115 (PE); Shennongjia, Sino–Amer. Exped. 1061 (PE); • Shaanxi: Hanzhong, J. W. Wang & Z. C. Shi 109 (PE); Lüeyang, C. L. Tang 467 (PE); Nanzheng, K. T. Fu 6161 (PE); Ningqiang, T. N. Liou 11810 (PE 00274549, PE 00274550); Ningshan, H. W. Kung 3305 (PE), P. C. Kuo 1003 (PE); Pingli, P. Y. Li 4992 (PE); Taibai, C. G. Ma et al. 308 (PE 01824224, PE 01824225, PE 01824226); Yangxian, P. C. Kuo 2003 (PE), K. T. Fu 5245 (PE), H. W. Kung 3530 (PE), J. X. Yang 2075 (PE); Ziyang, P. Y. Li 4765 (PE), 4829 (PE), 6326 (PE), H. N. Qin et al. 18407 (PE); • Sichuan: Batang, D. E. Boufford et al. 35510 (PE), 35585 (PE), 35616 (PE); Baoxing, C. P’ei 814 (PE), S. S. Chang & Y. X. Ren 7470 (PE); Butuo, Sichuan, Econ. Pl. Exped. 5898 (PE); Dujiangyan, Z. T. Wang et al. 870015 (PE); Ebian, Z. X. Zhao 737 (PE), C. W. Yao 2890 (PE), S. L. Sun 987 (PE); Emei, T. N. Liou 10589 (PE), J. H. Xiong et al. 32869 (PE), W. P. Fang 3182 (PE), K. C. Kuan et al. 1858 (PE 00274512, PE 00274513), 1989 (PE 00274516, PE 00274517), 2508 (PE 00274514, PE 00274515), 2623 (PE 00274508, PE 00274509), K. H. Yang 57013 (PE), 57561 (PE), T. N. Liou & C. Wang 783 (PE 00274522, PE 00274523); Ganluo, Anonymous 4162 (PE 00274518, PE 00274608); Guangyuan, Y. Q. He 1577 (PE), T. N. Liou & C. Wang 207 (PE); Hanyuan, T. P. Wang 9491 (PE); Heishui, X. Li 73404 (PE), 73610 (PE); Jinchuan, X. Li 75360 (PE), G. Z. Zhu & X. Li 75666 (PE); Jiulong, Anonymous 4888 (PE), D. E. Boufford et al. 33040 (PE 01799277, PE 01799278); Kangding, W. K. Hu & C. Ho 11051 (PE), 10641 (PE); Leshan, Z. T. Guan 6327 (PE); Leibo, C. S. Cao 533 (PE), 607 (PE), 635 (PE), 1570 (PE); Lixian, C. S. Cao 1037 (PE); Luhuo, D. E. Boufford et al. 34765 (PE); Mabian, T. T. Yu 4174 (PE 00274507, PE 00274589, PE 00274613); Barkam, Anonymous 23467 (PE); Shimian, C. J. Xie 42525 (PE); Songpan, K. T. Fu 2109 (PE); Tianquan, W. P. Fang 3493 (PE), X. L. Jiang 35067 (PE), 37601 (PE), 38012 (PE), 35143 (PE), X. L. Jiang & J. H. Xiong 37754 (PE), K. L. Chu 4123 (PE), 4116 (PE), W. K. Hu & C. Ho 12002 (PE); Xiaojin, S. S. Chang & Y. X. Ren 6416 (PE); Xinlong, D. E.Boufford et al. 34132 (PE), 36291 (PE), 36269 (PE), 37281 (PE); Ya’an, T. P. Wang 8527 (PE), 8361 (PE), K. C. Kuan et al. 2498 (PE); Yuexi, Sichuan, Econ. Pl. Exped. 3724 (PE); Precise locality unknown, Anonymous 45 (PE), C. P’ei 8062 (PE), H. Smith 13564 (PE), Y. C. Yang 3547 (PE), West China Acad. Sci. 3120 (PE), 4123 (PE), C. L. Wu 12205 (PE); • Xizang: Bomê, Z. C. Ni et al. 1428 (PE), H. N. Qin et al. 362 (PE), T. S. Ying & D. Y. Hong 650124 (PE); Qamdo, D. E. Boufford et al. 32367 (PE 01799281, PE 01799282); Cona, Anonymous 75–1622 (PE 00532438, PE 00532439, PE 00532440); Gyirong, Qinghai–Xizang Exped. Vegetation Team 4678 (PE), Qinghai–Xizang Exped. 6966 (PE 00274661, PE 00274669), Jomda, D. E. Boufford et al. 31359 (PE); Riwoqê, D. E. Boufford et al. 32163 (PE); Nyingchi, Z. C. Ni et al. 34 (PE 00274675, PE 00274676), H. N. Qin et al. 193 (PE); Nyalam, Xizang Med. Herb Exped. 1505 (PE 00274666, PE 01532300), Y. T. Zhang & K. Y. Lang 4575 (PE 00274667, PE 00274668), H. N. Qin et al. 744 (PE 01717594, PE 01717595); Yadong, Qinghai–Xizang Exped. 2142 (PE 00274664, PE 00274665), Qinghai–Xizang Supplement Team 750299 (PE 00274671, PE 00274672), Anonymous 75–901 (PE 00532436, PE 00532437); • Yunnan: Dali, George Forrest 11670 (PE); Deqin, K. M. Feng 5357 (PE 00274654, PE 00274655), Anonymous 75–766 (PE); Kunming, Z. Y. Liu 19198 (PE); Shangri–la, H. N. Qin et al. 609 (PE); Yiliang, Northeast Yunnan Exped. 943 (PE); Precise locality unknown, T. P. Zhu 235 (PE), George Forrest 11025 (PE), Anonymous 4580 (PE); India • Carhoul: Mana, M. P. Edgeworth 16 (K 000890396); Nepal • Kamaon: Gossain-Than, N. Wallich 2974/84 (K 001118307).

China • Sichuan, Songpan, alt. 2400 m, Roadside, 22 Oct 1937, T. P. Wang 7896 (holotype, PE 00274683!) (Suppl. material 1: fig. S4).

Leaves elliptic-lanceolate, 2–3.5 × 0.5–1 cm, abaxially white, appressed tomentose, adaxially glabrous. Phyllaries outer ovate, puberulent or glabrate. This variety is similar to Homostylium argyropholium. It may be intermediate between H. argyropholium and H. polium.

China, Sichuan (Songpan). Ca. 2400 m.

Subalpine.

The varietal name “discolor” is derived from the Latin “dis-” meaning “apart” or “opposite”, and “-color” meaning “color”. The name likely refers to a color variation (abaxially white leaves) compared to Homostylium albescens var. albescens.

China • Sichuan: Songpan, T. P. Wang 7896 (PE 00274683), T. P. Wang 7924 (PE).

China • Yunnan, Lijiang, shady, rocky situations, side valleys on the eastern flank, Lat. 27'15°N, alt. 9500–11000 ft, July 1906, G. Forrest 2508 (holotype, E 00385621!; isotype, P 00711686!) (Suppl. material 1: figs S5, S6).

Leaves narrowly to broadly lanceolate, 5–12 cm, both surfaces glabrous, sometimes young leaves abaxially sparsely tomentose on midvein only. Phyllaries outer ovate to lanceolate, glabrous. The leaves are similar in shape to those of Homostylium albescens var. albescens, but are often shorter and narrower.

China (Chongqing, Gansu, Xizang, Hubei, W Sichuan, N Yunnan). 800–3000 m.

Subalpine.

The varietal name “glabratum” is derived from the Latin “glaber”, meaning “smooth” or “hairless”, combined with the neuter suffix “-atum”, which indicates “possession”. The name likely refers to the abaxially smooth, hairless leaf surface of this variety.

China • Chongqing: Chengkou, T. L. Dai 103779 (PE); Nanchuan, G. F. Li 64223 (PE), J. H. Xiong & Z. L. Zhou 92453 (PE); Wuxi, G. H. Yang 65505 (PE), • Gansu: Kangxian, Z. Y. Zhang 16874 (PE); Wenxian, Y. Q. He 936 (PE), J. X. Yang & Y. Q. He 3380 (PE); • Hubei: Xuan’en, H. J. Li 3852 (PE), 4689 (PE); Lichuan, G. X. Fu & Z. S. Zhang 1588 (PE 00274747, PE 00274748, PE 00274749); • Sichuan: Baiyu, D. E. Boufford et al. 37202 (PE); Baoxing, T. P. Soong 39045 (PE), K. L. Chu 3120 (PE); Butuo, Sichuan, Econ. Pl. Exped. 5898 (PE); Danba, D. Y. Hong et al. 95061 (PE); Ebian, Anonymous 145 (PE), Anonymous 146 (PE), Heishui, X. Li 74090 (PE), 73288 (PE), 73844 (PE), Jinchuan, X. Li 75077 (PE), 75152 (PE), 75171 (PE), 75231 (PE), 75270 (PE), 75288 (PE), 75387 (PE), 75411 (PE), 75457 (PE), 75460 (PE), 75475 (PE), 75493 (PE), 75557 (PE), 75702 (PE), 75908 (PE), 76223 (PE), 76273 (PE), 76304 (PE), 76531 (PE), 76585 (PE), 76761 (PE), 77993 (PE), 78055 (PE), 78242 (PE), 78362 (PE), 78490 (PE), 78509 (PE 00274889, PE 00274891), 78611 (PE), 78714 (PE 00274757, PE 00274758), G. Z. Zhu & X. Li 75578 (PE), 75629 (PE), 75677 (PE), 75816 (PE), G. Z. Zhu 75052 (PE), Anonymous 9474 (PE), Anonymous 75848 (PE), Kangding, W. G. Hu & X. L. Jiang 36862 (PE), X. L. Jiang 37151 (PE), 37044 (PE), 37010 (PE), C. S. Liu 1058 (PE 00274780, PE 00274797); Lixian, Anonymous 4544 (WU), C. S. Cao 21 (PE), 48 (PE), 149 (PE), 1203 (PE), Z. He & Z. L. Zhou 4216 (PE); Luhuo, Wei L. Chen et al. 7304 (PE); Barkam, X. Li 72379 (PE), 72567 (PE), 71852 (PE), 71944 (PE), X. Li & J. X. Zhou 72668 (PE), J. X. Zhou & X. Li 72729 (PE), Anonymous 23273 (PE); Meigu, Sichuan, Econ. Pl. Exped. 1677 (PE), Anonymous 13096 (PE); Mianning, S. F. Zhu 20327 (PE); Muli, K. M. Feng 2923 (PE), T. T. Yu 14100 (PE); Shimian, C. J. Xie 42771 (PE), 42413 (PE); Tianquan, X. L. Jiang 35226 (PE); Wenchuan, Anonymous 8267 (PE); Xiangcheng, Veg. Exped. 3233 (PE); Xiaojin, P. X. Li 10030 (PE), J. Zhou E572 (PE), S. S. Chang & Y. X. Ren 6481 (PE); Yajiang, D. E. Boufford et al. 35796 (PE), West China Acad. Sci. 4116 (PE), S. X. Jia 360 (PE), H. Smith 12593 (PE), Anonymous 102001 (PE), Y. W. Tsui 5965 (PE), X. Li 76708 (PE), 76954 (PE), 76874 (PE), 76932 (PE), S. F. Zhu 20327 (PE), Anonymous 5675 (PE), Sichuan Veg. Exped. 2397 (PE); • Xizang: Zayü, C. W. Wang 66522 (PE), Jin W. Zhang 982 (PE), Chagyab, Qinghai-Tibet Exped. 12287 (PE); Markam, Qinghai-Tibet Exped. 11980 (PE 01824813, PE 01824814); Mainling, Xizang Med. Herb Exped. 4226 (PE); • Yunnan: Lijiang, G. Forrest 2508 (E 0038562, P 00711686); Shangri-la, Zhongdian Exped. 2091 (PE 00274836, PE 00274837).

India, George Forrest 2508 (lectotype, designated here, E 00385621!) (Suppl. material 1: fig. S7).

Leaves elliptic-lanceolate, abaxially brown pubescent on veins or sometimes totally, glandular, base attenuate, apex acuminate. Phyllaries outer narrowly lanceolate, puberulent. The main differences from the type variety include leaves long-elliptic-lanceolate, base attenuate, apex acuminate, abaxially brown tomentose along veins or entirely, stem often more robust.

China (W and N Sichuan, Xizang, Yunnan); N India. 1900 to 3900 m.

Subalpine.

The varietal name “salignum” is derived from the Latin “salix”, meaning “willow” and the neuter suffix “-gnum”, meaning “pertaining” or “resembling”. The name likely refers to the resemblance of this variety to willow leaves, particularly in shape.

China • Sichuan: Baoxing, T. P. Soong 38993 (PE), 39214 (PE); Daofu, S. Jiang et al. 2351 (PE); Jinchuan, X. Li 76838 (PE), 78065 (PE), 78362 (PE), 78490 (PE), 78611 (PE); Kangding, S. Jiang et al. 9763 (PE); Meigu, Sichuan, Econ. Pl. Exped. 1677 (PE); Muli, T. T. Yu 6605 (PE 00274903, PE 00274904), 14100 (PE); Xiaojin, G. Z. Liu 408 (PE), S. S. Chang & Y. X. Ren 5875 (PE), 6715 (PE), 6798 (PE), 6994 (PE); Yajiang, Z. Y. Luo et al. 527 (PE), Precise locality unknown, C. W. Wang 65280 (PE), 66060 (PE), K. L. Chu 7595 (PE 00274885, PE 00274886), Min. Forest. s.n. (PE); • Xizang: Precise locality unknown, J.P.A. David s.n.; • Yunnan: Binchuan, T. N. Liou 22098 (PE), 22103 (PE); Deqin, T. T. Yu 9438 (PE 00274956, PE 00274957), 9858 (PE 00274926, PE 00274927), 10535 (PE 00274906, PE 00274907), K. M. Feng 5535 (PE), 5644 (PE 00274917, PE 00274918), C. W. Wang 64762 (PE), 69994 (PE), H. T. Tsai 54400 (PE), 54416 (PE); Gongshan, C. W. Wang 67082 (PE), K. M. Feng 8391 (PE); Heqing, R. C. Ching 23614 (PE), 23937 (PE 00274910, PE 00274933); Lanping, H. T. Tsai 56284 (PE); Lijiang, T. T. Yu 15239 (PE), R. C. Ching 30994 (PE 00274912, PE 00274913), K. M. Feng 21327 (PE); Shangri-la, T. T. Yu 11550 (PE 00274919, PE 00274920), 12390 (PE 00274958, PE 00274959), 12522 (PE 00274914, PE 00274915), K. M. Feng 2749 (PE), Zhongdian Exped. 1508 (PE 00274937, PE 00274938); Precise locality unknown, T. T. Yu 15239 (PE 00274908, PE 00274909), 19693 (PE), 20823 (PE), 20925 (PE 00274953, PE 00274954), 22617 (PE), K. M. Feng 1210 (PE), H. T. Tsai 52981 (PE), Zhongdian Exped. 1413 (PE 00274939, PE 00274940); India • Unknown: Precise locality unknown, George Forrest 2508 (E 00385621).

In Nesom (2020g), the type specimen for this variety was designated as “Xizang. J.P.A. David s.n.”, with neither a collection number nor a specimen number specified. According to the protologue, the holotype specimen number for Homostylium albescens var. salignum was also not seen. A careful search was conducted at the PE Herbarium. More than 190 specimens of this variety were found, but still no holotype was designated. Among them, the specimen E00385621 (George Forrest 2508) (Suppl. material 1: fig. S7) closely matched the illustration in the original publication. Therefore, this specimen was designated as the lectotype of this variety.

China • Xizang, Chamdo, alt. 13000ft, 6 August 1933, F. Kingdon-Ward 10752 (holotype, E 00385688!; isotype, BM 000945772!) (Suppl. material 1: figs S8, S9).

Leaves ovate or ovate to oblong-lanceolate, 4–10 × 1–2.5 cm, abaxially brown hairy on veins, densely glandular. It is clearly similar to H. albescens var. salignum but has smaller leaves, more glandular points, and different hairiness.

China, S and E Xizang (Yadong, Bomi, Ranwu, Zayü, etc.), W and SW Sichuan, NW Yunnan (Weixi, Deqin, etc.); India. 1900 to 3900 m.

Subalpine.

The varietal name “glandulosum” is derived from the Latin “glandula”, meaning “gland”, and the neuter suffix “-osum”, meaning “full of” or “abundant in”. The name likely refers to the abundant glands on this variety, suggesting glandular leaves on the abaxial surface.

China • Sichuan: Dege, Y. W. Tsui 5082 (PE); Precise locality unknown, W. G. Hu & C. Ho 10929 (PE); • Xizang: Bomê, T. S. Ying & D. Y. Hong 650124 (PE 01825438, PE 00274703), 650193 (PE 00274701, PE 00274702), 651069 (PE), S. Z. Cheng & B. S. Li 173 (PE), 486 (PE), 617 (PE 01825439, PE 01825440); Chagyab, Qinghai-Tibet Exped. 12287 (PE), Jin W. Zhang 1098 (PE), 6316 (PE); Zayü, Z. C. Ni et al. 1091 (PE 00274679, PE 00274680); Cona, C. Y. Wu et al. 75-1099 (PE); Qamdo, F. Kingdon-Ward 10752 (E 00385688, BM 000945772), G. C. Xia et al. 1326 (PE), 1390 (PE); Gongjue, Qinghai-Tibet Exped. 12553 (PE 00274744, PE 00274745), J. S. Yang 91-493 (PE); Gyaca, Xizang Med. Herb Exped. 4551 (PE); Nyingchi, B. S. Li et al. 6410 (PE), Z. C. Ni et al. 0034 (PE 00274675, PE 00274676); Lhünzê, G. X. Fu & Jin W. Zhang 01159 (PE); Mainling, B. S. Li & S. Z. Cheng 05549 (PE), Z. C. Ni et al. 3052 (PE); Mêdog, B. S. Li & S. Z. Cheng 01135 (PE 01824803, PE 01824804); Yadong, G. X. Fu & Jin W. Zhang 1080 (PE), G. X. Fu & Jin W. Zhang 1122 (PE), G. X. Fu 907 (PE), Precise locality unknown, C. W. Wang 66550 (PE), S. X. Jia 315 (PE), 418 (PE), 682 (PE); • Yunnan: Deqing, T. T. Yu 8459 (PE 00274697, PE 00274698); Weixi, C. W. Wang 68048 (PE 00274699, PE 00274700).

China • Sichuan, Muli, alt. 2800 m, 31 July 1915, Hand.-Mazz. 7350 (holotype, WU 0061122!; isotype, A 00003821!) (Suppl. material 1: figs S11, S12).

Leaves elliptic-lanceolate, 7–20 × 1–5 cm, abaxially densely white or gray-white tomentose or cottony, base attenuate, apex acuminate. Phyllaries outer oblong or lanceolate. The tomentose of this variety is the same as that of Homostylium albescens var. limprichtii, but its leaf shape is similar to that of H. albescens var. salignum.

China, W Sichuan (Jinchuan, Heishui, etc.), Chongqing (Wushan, Nanchuan, etc.), Guizhou, NW Yunnan (Dali), Gansu, and S Shaanxi.

Temperate biome and subalpine.

The varietal name “harrowianum” is derived from the name of Harrow, with the Latin neuter adjectival suffix “-ianum”, indicating possession or association. The variety was likely named in honor of Harrow, either the collector name or the place of collection in London, Britain.

China • Chongqing: Precise locality unknown, T. N. Liou 9842 (PE 00274690, PE 00274691); • Gansu: Wenxian, Z. Y. Zhang 14794 (PE); • Guizhou: Chishui, Bijie Exped. 1243 (PE 00274634, PE 00274635); Zunyi, Sichuan-Guizhou Exped. 1542 (PE 00274637, PE 00274638, PE 00274640); • Shaanxi: Mianxian, S. Jiang et al. 232 (PE), T. N. Liou & P. C. Tsoong 3411 (PE), • Sichuan: Xiangcheng, S. Jiang et al. 9611 (PE); Kangding, K. C. Kuan et al. 77 (PE 00274687, PE 00274688, PE 00274689); Lixian, C. L. Wu 33209 (PE), S. Jiang et al. 1958 (PE); Muli, Hand.-Mazz. 7350 (WU 0061122, A 00003821); • Yunnan: Dali, T. N. Liou 17471 (PE 00274716, PE 00274728), 17631 (PE), 20950 (PE), 21031 (PE), R. C. Ching 22719 (PE), H. C. Wang 770 (PE 00274659, PE 00274660), 865 (PE), 990 (PE), 1140 (PE 00274723, PE 00274725), 1144 (PE), 1450 (PE), 1458 (PE 00274717, PE 00274730), 1574 (PE 00274721, PE 00274727), 4302 (PE), 4404 (PE), H. T. Tsai 53877 (PE), G. Forrest 4004 (E 00385622); Lijiang, G. Forrest 2508 (E 00385621, P 00711686).

The autonyms take priority over other variety names established simultaneously, as well as over other synonyms, according to Articles 11.6 of ICN (Turland et al. 2018). Aster harrowianus var. harrowianus (1912), established alongside A. harrowianus var. glabratus (1912), takes precedence over A. limprichtii var. gracilior (1936) and A. albescens var. gracilior (1938). Accordingly, for this new combination, we adopted the varietal epithet “harrowianus” and adjusted it to the neuter form “harrowianum” to match the gender of Homostylium.

China • Sichuan, Batang-Litang, alt. 3400 m, 21 August 1914, H. W. Limpricht 2226 (lectotype, designated here, WRSL S07-7760!; isolectotypes, A 00003820!, PE no. 32347!, WU 0061126!) (Suppl. material 1: figs S13–S16).

Leaves elliptic or oblong, 3–7 × 1–3 cm, abaxially densely white or gray-white tomentose or cottony, base broadly cuneate or rounded. Phyllaries outer ovate, sparsely tomentose. The main differences from the type variety include leaves elliptic or oblong, base broadly cuneate or rounded, apex obtuse, abaxially densely tomentose or cottony, white to gray-white.

China, W and NW Sichuan (Songpan, Maoxian, Lixian, Kangding, Heishui, Hanyuan), Xizang, and W Gansu (Xigu, Longnan). 2400–3100 m.

Temperate biome and subalpine.

The varietal name “limprichtii” is derived from the name of German botanist and teacher Hans Wolfgang Limpricht, with the Latin eponymic suffix “-ii”. The variety was likely named in honor of Mr. Limpricht, the collector of the type specimens.

China • Gansu: Longnan, T. P. Wang 14702 (PE 00274842, PE 00274845), 15235 (PE), 15212 (PE); • Sichuan: Heishui, X. Li & J. X. Zhou 73734 (PE); Kangding, H. Smith 13414 (PE); Maoxian, C. Ho & Z. L. Zhou 12984 (PE); Songpan, T. P. Wang 7760 (PE); Hanyuan, T. P. Wang 8706 (PE); Jiuzhaigou, P. Q. Li 149 (PE), H. Smith 10355 (PE); Batang-Litang, H. W. Lim­pricht 2226 (WRSL S07-7760, A 00003820, PE no. 32347, WU 0061126); • Xizang: Zayü, Qinghai-Tibet Exped. 161 (PE 00274856, PE 00274857), Z. C. Ni et al. 195 (PE 00274677, PE 00274678).

Nesom (2020g) only provided the type specimen information with collection locality, collector, and collection number (Xizang, Limpricht 2226) for this variety, without specifying an exact specimen number. According to the protologue, the holotype specimen number for Homostylium albescens var. limprichtii was not seen. A careful search was conducted at the PE Herbarium. Forty-three specimens of this variety were found, but still no holotype was designated. Among them, the specimen WRSL S07-7760 (H. W. Limpricht 2226) (Suppl. material 1: figs S13–S16) closely matched the illustration in the original publication. Therefore, this specimen was designated as the lectotype of this variety. The duplicate specimens (syntypes) from the same collections were then treated as isolectotypes.

China • Sichuan, Lixian, C. Ho & Z. L. Zhou 13318 (holotype, PE 00274858!) (Suppl. material 1: fig. S17).

Stems yellow-brown pilose and white arachnoid. Leaves elliptic or ovate-lanceolate, 10–15 × 5–7 cm, adaxially arachnoid pilose, reticulate veins prominent, abaxially sparsely pilose, midvein white villous, base rounded or broadly cuneate, margin subentire, apex acute or subrounded. Phyllaries outer ovate, sparsely puberulent. The leaf shape of this variety differs from all other varieties.

China, W Sichuan (Lixian, Maoxian, Wenchuan).

Subalpine.

The varietal name “megaphyllum” is derived from the Greek “mega-”, meaning “large” or “grate”, and the “-phyllon”, meaning “leaf”, combined with the Latin neuter suffix “-um”. The name likely refers to this variety having larger leaves than other varieties.

China • Sichuan: Lixian, C. Ho & Z. L. Zhou 13318 (PE).

China • Yunnan, Lijiang, Ninglang and Yongsheng, 15 May 1922, J. F. Rock 5164 (holotype, WU, not seen; isotypes, E 00385623!, WU 1937-0004375!) (Suppl. material 1: figs S18, S19).

Leaves oblong-lanceolate, 4–9 × 1–2 cm, abaxially on midvein or totally white pilose, adaxially sparsely hispidulous, flat. Phyllaries outer sparsely hairy. achenes densely pilose. The main differences from type variety include leaves oblong-lanceolate, abaxially sparsely pilose along the midvein or entirely, adaxially sparsely hispid, achenes densely villous.

Common. SW China (W Sichuan, E Xizang, NW Yunnan). 2800–4000 m.

Subalpine.

The varietal name “pilosum” is derived from the Latin “pilus”, meaning “hair”, combined with the neuter suffix “-osum”, meaning “full of” or “abundant in”. The name likely refers to abundant pilose on the abaxial surface of leaves.

China • Sichuan: Dege, Anonymous 115 (PE); Daocheng, Bot. Exped. 2436 (PE); Kangding, H. Smith 10436 (PE), 12912 (PE), 13990 (PE); Jinchuan, X. Li 78185 (PE); Lixian, S. Jiang et al. 1608 (PE); Precise locality unknown, S. Jiang et al. 2018 (PE); • Xizang: Nyingchi, Xizang Med. Herb Exped. 3450 (PE), D. E. Boufford et al. 30173 (PE), Y. T. Zhang & K. Y. Lang 1315 (PE 00274876, PE 00274877), B. S. Li et al. 6247 (PE); Mainling, Qinghai-Tibet Exped. 1961 (PE 00274878, PE 00274879), Xizang Med. Herb Exped. 3724 (PE), Qinghai-Tibet Supplement Team 750817 (PE 00274874, PE 00274875); Precise locality unknown, B. S. Li & S. Z. Cheng 5376 (PE 01824815, PE 01824816); • Yunnan: Dali, R. C. Ching 22919 (PE), Qin et al. 649 (PE); Qiaojia, B. X. Sun et al. 908 (PE); Lijiang, J. F. Rock 5164 (E 00385623, WU 1937-0004375).

China • Yunnan, Qinghua university 5895 (holotype, PE 02050377!) (Suppl. material 1: fig. S20).

Leaves oblong-lanceolate, adaxially hispidulous, reticulate veins prominent, areoles of reticulate veins with foamy process. Leaf shape is similar to that of the previous varieties, but with more prominently raised reticulate venation, making the interveinal areas bullate, adaxially sparsely hispidulous.

China, NW Yunnan (Dali) and W Sichuan (Huili).

Subalpine.

The varietal name “rugosum” is derived from the Latin “ruga”, meaning “wrinkle” or “fold”, combined with the neuter suffix “-osum”, meaning “full of” or “abundant in”. The name likely refers to the uneven leaf surface, indicating the presence of a foamy process on the adaxial surface.

China • Sichuan: Huili, T. T. Yu 1605 (PE); Kangding, Soulie 900 (PE 02050375, PE 02050376); • Yunnan: Precise locality unknown, Qinghua university 5895 (PE 02050377).

The polymorphism of H. albescens is evident. In addition to the varieties listed herein, there is also a variety of Homostylium albescens var. niveum distributed in Sikkim. According to Grierson (1964), its abaxial leaf surface is covered with cottony tomentum. The plants observed in western China with a cottony tomentose abaxial leaf surface should likely be merged into either H. albescens var. limprichtii or H. albescens var. harrowianum.

India • Sikkim, Jakpho, Napa Hill, alt. 3017 m, 25 Oct. 1885, C. B. Clarke 41356 (holotype, E 00531283!; isotype, K 00089039!) (Suppl. material 1: figs S23, A24).

Leaves abaxially densely cottony tomentum.

China, Chongqing, W Sichuan (Emei Mount., Xiaojin), SE Shaanxi (Pingli); N India (Sikkim).

Subalpine or subarctic biome.

The varietal name “niveum” is derived from the Latin “nix”, meaning “snow”, combined with the neuter suffix “-eum”. The name likely refers to its habitat in the snow-covered subalpine and subarctic biome, or to the abaxial leaf densely covered in white tomentum.

China • Chongqing: Nanchuan, J. H. Xiong & Z. L. Zhou 94046; • Shaanxi: Pingli, Field Collection Team of Western Xida’an Kang District 20132; • Sichuan: Emei, W. P. Fang 3297, 3182; Xiaojin, T. T. Yu 2429; India • Sikkim: Jakpho, C. B. Clarke 41356 (E 00531283, K 00089039).

The new combination Sinosidus albescens (DC.) G.L.Nesom proposed by Nesom (2020g) did not include this variety, although it comprised ten varieties (including the type variety).

China • Sichuan, Kangding (Tatien-lu), frutex fere metralis in declivo aprico, 2 Jul 1922, H. Smith 2258 (holotype, UPS, v-080214!) (Suppl. material 1: fig. S25).

Shrubs, 93–228 cm tall. Leaves subleathery, alternate, elliptic, oblong, or lanceolate-ovate, 1–4 × 0.3–1.6 cm; midvein abaxially prominent, lateral veins apparent, pinnate; margin subundulate to entire, revolute, glandular-punctate, upper leaves smaller; adaxially green, moderately scabridulous, minutely glandular, resin-dotted, scabrous; abaxially densely lanate or greyish-white arachnoid-tomentose. Capitula 4–10(-20), with 15–20 ray florets, in corymbiform synflorescences, terminal on axillary branches. Peduncles slender, 2–7 mm, bracteoles linear. Involucres campanulate, ca. 5 mm long, 8 mm in diameter. Phyllaries 4–5 seriate, imbricate, pubescent to glabrescent, outer phyllaries oblong, 1 × 0.5 mm, inner phyllaries ovate, 4–5 × 1 mm.

Figure 4. 

Homostylium argyropholium (Hand.-Mazz.) Z.X.Fu. A. Habit; B. Habitat; C. Capitula (lateral view, showing the involucre); D. Abaxial surface of leaves. Photographed by Z. X. Fu from Z. X. Fu 2944 (PE).

China, S and W Sichuan, SE Xizang, NW Yunnan (Fig. 5).

Figure 5. 

Distribution of Homostylium argyropholium. China is centrally located on the map.

Alpine and subalpine slopes, under forests, grasslands, riverbanks. 2100–3100 m.

Flowering May to October. Fruiting August to October.

It is derived from the Greek “argyros”, meaning “silver”, and “pholis”, meaning “skin” or “scale”, combined with the Latin neuter suffix “-um”. The specific epithet likely refers to the silvery, scale-like, glandular punctate on the leaves.

This species is similar to Homostylium albescens var. discolor. However, it can be distinguished by its fewer capitula borne at the branch tips, narrower involucre, and white buds in the leaf axils. H. polium bears soft and white arachnoid-tomentose on the abaxial leaves, particularly resembling H. argyropholium. However, it has much smaller leaves, and inflorescences borne on lateral branches, allowing for easy differentiation from H. argyropholium.

Leaves abaxially densely tomentose or pubescence, secondary veins abaxially not prominent, apex acute or abruptly acute, rarely rounded. Peduncles densely tomentulose. Involucres 4–5 mm. Phyllaries 4-seriate. The leaves exhibit considerable variation, with apices either obtuse or acuminate.

Common. China, Sichuan (Damba, Jinchuan, Lixian, Barkham, Xiaojin), and Xizang (Basu).

Subalpine.

China • Sichuan: Kangding (Tatien-lu), H. Smith 2258 (UPS v-080214); Danba, Z. X. Fu 2970 (PE), 2971 (PE), 2972 (PE); Jinchuan, Z. X. Fu 2993 (PE), 2994 (PE), 2995 (PE), 2996 (PE), 2997 (PE), 2998 (PE), 2999 (PE), 3001 (PE), X. Li 76624 (PE), 77595 (PE 00275057, PE 00274598), 75154 (PE), 77904 (PE), 75124 (PE), D. Y. Hong et al. 95047 (PE); Lixian, C. S. Cao 193 (PE), 1569 (PE), G. J. Zhang 145 (PE), 146 (PE), Z. X. Fu 3054 (PE), 3055 (PE), 3056 (PE), 3058 (PE); Barkam, T. Y. Chang & H. F. Zhou 23111 (IBSC, KUN), Z. X. Fu 3003 (PE), 3010 (PE), 3011 (PE), 3012 (PE), 3013 (PE), 3015(PE), 3016 (PE), 3017 (PE), S. Jiang & C. L. Jin 1026 (PE 00275056, PE 01776701, PE 01822231), T. Y. Chang & H. F. Zhou 22631 (PE, KUN, IBSC), 23024 (PE, KUN, IBSC), Z. B. Feng 960306 (HX), G. J. Zhang 148 (PE), 151 (PE), 152 (PE), 153 (PE), T. Y. Chang & H. F. Zhou 23467 (PE, KUN); Xiaojin, Z. X. Fu 2944 (PE), J. Zhou 86 (PE, IBSC), H. N. Qin, S. X. Yu & J. Y. Wu 17087 (PE); • Xizang: Baxoi, J. S. Yang 90-251 (PE).

China • Sichuan, Lixian, alt. 2700 m, 8 July 1930, F. T. Wang 21626 (holotype, PE 00275069!) (Suppl. material 1: fig. S26).

Leaves abaxially densely white tomentum, secondary veins abaxially not prominent, apex obtuse or rounded. Peduncles densely white tomentum. Involucres 4–5 mm. Phyllaries 4-seriate. The leaves’ coloration could distinctly differentiate it from the other varieties.

China, W Sichuan (Jinchuan, Luding, Lixian, Barkam, Maoxian, Yanyuan), and NW Yunnan (Lijiang).

Subalpine.

The varietal name “niveum” is derived from the Latin “nix”, meaning “snow”, combined with the neuter suffix “-eum”. The name likely refers to its abaxial leaf and inflorescence peduncles densely covered in white tomentum.

China • Sichuan: Jinchuan, X. Li 77625 (PE); Luding, Anonymous 6828 (PE 01824233, CDBI 0141863, CDBI 0141864, CDBI 0141865); Barkam, P. X. Li 10061 (PE); Maoxian & Lixian, C. Ho & Z. L. Zhou 13058 (PE); Lixian, F. T. Wang 21626 (PE 00275069); • Yunnan: Lijiang, W. L. He & C. Y. Zhao 20344 (PE, KUN), R. C. Ching 20344 (KUN).

China • Sichuan, Barkam, alt. 2700 m, 18 July 1957, X. Li 23091 (holotype, PE 00275072!; isotype, KUN, not seen) (Suppl. material 1: fig. S27).

Leaves abaxially sparsely tomentose, secondary veins abaxially prominent. Involucres 5–6 mm. Phyllaries 5-seriate. The lateral veins of abaxial leaves in this variety are prominently elevated and covered with fine tomentum, differentiating it from the type variety.

China, W Sichuan (Barkam, Jinchuan). Jinchuan is a new distribution record at the county level.

Subalpine.

The varietal name “paradoxum” is derived from the Greek “paradoxos”, meaning “contrary to expectation” or “unexpected”, combined with the Latin neuter suffix “-um”. The name likely refers to a distinctive or unexpected characteristic that distinguishes this variety from others.

China • Sichuan: Barkam, T. Y. Chang & H. F. Zhou 23091 (PE, IBSC, KUN, QTPMB), Z. X. Fu 3004 (PE), 3005 (PE), 3006 (PE), 3007 (PE), 3008 (PE), 3014 (PE), 3018 (PE); Jinchuan, Z. X. Fu 3002 (PE).

China • Xizang, Bomê, Tangme (Tongmai), Tsangpo-Yigrong Confluence, alt. 7000 ft, 3 June 1947, F. Ludlow, G. Sherriff & H. H. Elliott 13074 (holotype, E 00385686!; isotype, BM 000945773!) (Suppl. material 1: figs S28, S29).

Shrubs, 126–192 cm tall. Leaves alternate, ovate, (4-)6–9 × (2-)2.4–4.8 cm, venation prominently pinnate, intercostal glossy; margin entire, revolute, abaxially sparsely strigillose, glossy between minor veins, sparsely minutely glandular; adaxially glabrous or glabrate, sparsely minutely glandular, midvein sparsely strigillose. Capitula numerous, in terminal corymbiform synflorescences. Peduncles 1.5–2 cm long. Involucres campanulate, 5–7 mm in diameter. Phyllaries 3–4 seriate, imbricate, 1.5–3 × 1 mm, outer series ovate, shorter, inner series ovate, 6–7 × 0.5 mm.

Figure 6. 

Homostylium fulgidulum (Grierson) Z.X.Fu. A. Habit; B. Habitat; C. Abaxial surface of leaves; D. Capitula. Photographed by G. J. Zhang from B. H. Jiao & G. J. Zhang 294 (PE).

China, SE Xizang (Bomê and Nyingchi). 2200–3000 m (Fig. 7).

Figure 7. 

Distribution of Homostylium fulgidulum. China is centrally located on the map.

Margins of submontane forest and hillside shrublands.

Flowering June to August. Fruiting June to August.

The name “fulgidulum” is derived from the Latin “fulgidus”, meaning “shining” or “radiant”, combined with the Latin neuter suffix “-ulum”, meaning “diminutive”. The specific epithet likely refers to its abaxially glossy intercostal veins on the surface of leaves.

China • Xizang: Bomê, T. S. Ying & D. Y. Hong 650705 (PE), Jin W. Zhang & J. T. Wang 440 (PE), G. J. Zhang & B. H. Jiao 294 (PE), W. L. Zheng 293 (XZ), D. E. Boufford et al. 29838 (PE), F. Ludlow, G. Sherriff & H. H. Elliott 13074 (E 00385686, BM 000945773); Nyingchi, B. S. Li et al. 6410 (PE), Xizang Med. Herb Exped. 3542 (PE), T. Naito et al. 1099 (PE), G. Yao et al. 1282 (XZ), W. L. Zheng 985 (XZ), W. L. Zheng et al. 3236 (XZ), W. L. Zheng et al. 3239 (XZ), Anonymous 22 (XZ).

Figure 8. 

Homostylium fulgidulum (Grierson) Z.X.Fu. A. Habit; B. Capitulum; C. Involucral bracts; D. Ray floret; E. Disc floret; F. Floret with pappus bristle and removed achene; G. Style branches of disc floret; H. Stamen of disc floret; I. Outer pappus bristle; J. Inner pappus bristle. Drawn by Z. J. Chen.

This species closely resembles Homostylium albescens. However, it could be differentiated from the latter by its ovate, larger, both surfaces nearly glabrous leaves, and abaxially glossy intercostal veins.

China • Xizang, Nangxian, Kyimdong Dzong, F. Kingdon-Ward 11993 (holotype, BM 000945771!) (Suppl. material 1: fig. S30).

Dwarf shrubs, cespitose, 12–36 cm tall. Leaves alternate, elliptic to oblanceolate, 0.3–1.7 × 0.19–0.33 cm, leathery, margins entire or (1-)2-serrate-spinose, strongly revolute, adaxially dark green, glabrate, arachnoid, or sparsely sericeous, abaxially densely white tomentose. Capitula 1–3, terminal on lateral branches. Peduncles 1.5–3 cm long, sparsely strigose, with few subulate bracteoles. Involucres subcampanulate, 4–5 mm in diameter. Phyllaries 4-seriate, imbricate, outer phyllaries extremely short, ovate-lanceolate, inner phyllaries linear-lanceolate, 5 × 0.6 mm, 4–5 × as long as outer phyllaries.

Figure 9. 

Homostylium hypoleucum (Hand.-Mazz.) Z.X.Fu. A. Habit; B. Habitat; C. Upper portion of plant; D. Capitulum. Photographed by Z. X. Fu from Z. X. Fu 1475 (PE).

Endemic to China, SE Xizang (Lang, Gyaca, Mainling, and Zangbo Valley) (Fig. 10).

Figure 10. 

Distribution of Homostylium hypoleucum. China is centrally located on the map.

Arid mountain slopes of river valleys, rock crevices, woodland margins, and shrublands. 3000–3700 m.

Figure 11. 

Homostylium hypoleucum (Hand.-Mazz.) Z.X.Fu. A. Habit; B. Capitulum; C. Involucral bracts; D. Ray floret; E. Pappus bristle; F. Disc floret; G. Stamen of disc floret; H. Style branches of disc floret. Drawn by Z. J. Chen.

Flowering July to August. Fruiting August to September.

The specific epithet “hypoleucum” is derived from the Greek “hypo-”, meaning “under” or “beneath”, and “leucos”, meaning “white”, combined with the Latin neuter suffix “-um”. The name likely refers to the whitish coloration on the abaxial surface of the leaves (abaxially densely covered with thick white tomentum) in this species.

China • Xizang: Gyaca, B. Q. Xu et al. XiaNh–07zx–0639 (IBSC), Z. C. Ni et al. 2724 (PE 01836991, PE 01836993, PE 01836992), Qinghai–Xizang Supplement Team 750652 (PE 00275826, PE 00275825), Xizang Med. Herb Exped. 4399 (PE 01532326, PE 00275824); Nangxian, Z. X. Fu 1475 (PE), 1476 (PE), 1477 (PE), 1478 (PE), 1479 (PE), Qinghai–Xizang Exped. 7899 (PE 01532325, PE 01532063), Qinghai–Xizang Veget. Exped. 3314 (PE 01836952, PE 01532324), H. N. Qin et al. 554 (PE), J. Luo et al. L048 (QTPMB), Xizang Med. Herb Exped. 4250 (PE 00275828, PE 00275828), Z. C. Ni et al. 2757 (PE), F. Kingdon-Ward 11993 (BM 000945771); Mainling, Xizang Med. Herb Exped. 4302 (PE 01532328, PE 00275827).

This species can be easily distinguished from other shrubby Homostylium by its dwarf shrub habit and the persistent peduncles. Its leaf shape is similar to that of H. lavandulifolium. However, H. hypoleucum has relatively shorter and smaller leaves without adaxial papillate protrusions, capitula not arranged in a dense corymbose, broader involucres, and white pappus, which are diagnostic characters.

China • Sichuan, Muli, watershed of the Shou-chu river and Shou-chu valley, in dry gorge, alt. 2435–2900 m, June 1928, J. F. Rock 16273 (lectotype, designated by Nesom (2020g), W, not seen; isolectotypes, US 00145655!, A 00003817!, GH 00003818!, E 00413420!) (Suppl. material 1: figs S31–S34).

Shrubs, 48–124 cm tall. Leaves subleathery, narrowly linear, 1–4(-5.4) × 0.1–0.3(-0.53) cm, margins entire, revolute; midvein prominently glabrous, venation pinnate; adaxially green, rugose, resinous, very sparsely sericeous to nearly glabrous, papillate protrusions; abaxially densely gray-white tomentose; upper leaves smaller. Capitula 6–9 mm in diameter, 3–6 at ends of lateral branches or numerous in ± densely corymbiform synflorescences, terminal on current-year branches. Peduncles 2–6 mm long, with subulate bracteoles. Involucres obconical to campanulate, 5–7 × 4–7 mm. Phyllaries 4–5-seriate, imbricate, outer phyllaries ovate, ca. 1 mm × 0.5 mm, inner phyllaries longer, linear-lanceolate, sparsely tomentose, 4–5 × 0.7–0.9 mm.

Figure 12. 

Homostylium lavandulifolium (Hand.-Mazz.) Z.X.Fu. A. Habit; B. Habitat; C. Capitula; D. Abaxial surface of leaves. A, C. From FLPH Sichuan Exped. 151845 (PE), photographed by R. Ke, in Muli, Sichuan. B, D. From G. J. Zhang 170 (PE), photographed by G. J. Zhang.

Endemic to China, W Sichuan (Daocheng, Jiulong, Kangding, Muli, Yajiang), and NW Yunnan (Fig. 13).

Figure 13. 

Distribution of Homostylium lavandulifolium. China is centrally located on the map.

Subalpine stony slopes, riverbanks, and shrublands of aridly hot river valleys. 2000–2900 m.

Flowering June to August. Fruiting August to September.

China • Sichuan: Daocheng, Sichuan Veg. Exped. 2109 (CDBI); Jiulong, S. Jiang et al. 3918 (PE), T. T. Yu 6694 (PE), X. J. Yang 3935 (PE); Kangding, Z. J. Zhao et al. 114731 (CDBI), Y. S. Chen 7566 (PE); Muli, T. T. Yu 5894 (PE, IBSC), Y. S. Chen 7099 (PE), Y. S. Chen 7507 (PE), J.C.F. Rock 16273 (W, US 00145655, A 00003817, GH 00003818, E 00413420), FLPH Sichuan Exped. 151845 (PE); Yajiang, G. J. Zhang 170 (PE), Z. T. Guan56-0438 (PE), Z. P. Huang et al. 552 (PE), S. Jiang et al. 3202 (PE), Wei L. Chen et al. 6604 (PE).

Figure 14. 

Homostylium lavandulifolium (Hand.-Mazz.) Z.X.Fu. A. Habit; B. Capitulum; C. Involucral bracts; D. Ray floret; E. Disc floret; F. Stamen of disc floret; G. Style branches of disc floret; H. Pappus bristle. Drawn by Z. J. Chen.

The name “lavandulifolium” is derived from the Latin “lavandula”, referring to the genus Lavandula L., combined with the neuter suffix “-folium”, meaning “leaf” or “have the form of”. The specific epithet likely refers to the linear leaf shape of this species, resembling the distinctive form of Lavandula.

This species is particularly distinctive within Homostylium. The leaves of this species are narrowly linear, with revolute margins. The abaxial surface is pubescent, with prominent midrib, and cylindric achenes.

China • Xizang, Mêdog, Qarasa, gudeng-ganhua, in prato lapidoso secus marginem rivuli, alt. 1100 m, Dec. 1982, S. Z. Cheng & B. S. Li 2181 (holotype, PE 02050341!; isotypes, PE 02050372!, PE 02050373!, PE 02050374!) (Suppl. material 1: figs S35–S38).

Shrubs, 53–166 cm tall. Leaves alternate, subcoriaceous, median leaves oblong-lanceolate to narrowly oblong, (1-)3–4(-6.3) × 0.7–1.4 cm, margins entire, revolute, upper leaves gradually smaller, adaxially dark green, prominent venation, glossy, abaxially densely grayish-white to white tomentose except on midvein. Capitula numerous, small, radiate, 2–3 mm in diameter, with 4–6 ray florets, in densely corymbiform synflorescences, terminal on branch tips or in upper leaf axils. Peduncles slender, densely white tomentum. Involucres cylindrical or subcylindrical, 5.3–6.4 × 2 mm. Phyllaries 4–5-seriate, imbricate, subcoriaceous, outer phyllaries very small, ovate, ca. 1 mm long, sparsely pubescent, inner phyllaries oblong-lanceolate, 4.2–5.2 × 0.5–1 mm.

Endemic to China, SE Xizang, Mêdog (Fig. 15).

Figure 15. 

Distribution of Homostylium motuoense. China is centrally located on the map.

Riverbank slopes, roadside, and dry grassy slopes near villages. 980–1100 m.

Figure 16. 

Homostylium motuoense (Y.L.Chen) Z.X.Fu. A. Habit; B. Capitulum; C. Involucral bracts; D. Ray floret; E. Disc floret; F. Stamen of disc floret; G. Style branches of disc floret; H. Outer pappus bristle; I. Inner pappus bristle. Drawn by Z. J. Chen.

Flowering and fruiting ca. November.

The specific epithet “motuoense” is derived from the place name “Motuo” combined with the Latin neuter suffix “-ense”, meaning “from” or “of”. The name refers to the species being found and collected in Motuo (Mêdog) County, located in SE Tibet, China.

China • Xizang: Mêdog, S. Z. Cheng & B. S. Li 1796 (PE), 2075 (PE), 2181 (PE 02050341, PE 02050372, PE 02050373, PE 02050374).

Due to transportation difficulties in Mêdog County (Xizang), we were unable to photograph, collect, or sequence Homostylium motuoense. As a result, 6 Homostylium species, excluding H. motuoense, have been sequenced and used to reconstruct phylogenetic relationship within Aster and Astereae to date (Li et al. 2012; Zhang et al. 2015, 2019; Fu et al. 2019; Chen et al. 2024). The morphology of this species resembles H. lavandulifolium, but its leaves are narrowly oblong or elongated-lanceolate, with a glossy surface and prominent venation. The involucres are cylindrical. The ray florets 4–6, with two layers of pappus: the outer layer is very short, and the inner layer is 4 cm long, rough-haired. These characteristics make it easily distinguishable from H. lavandulifolium.

China • Sichuan, Xiaojin (=Nin Monkong Ting), head of Chin Ho Valley, alt. 7000–9000 ft, June 1908, E. H. Wilson 2233 (holotype, A 00003825!; isotype, US 01696632!) (Suppl. material 1: figs S39, S40).

Shrubs, 56–118 cm tall. Leaves subleathery, alternate, narrowly ovate to elliptic, 1.3–3.7 × 0.4–1.6 cm, margin entire, strongly revolute, adaxially green, scabridulous, verrucose-pubescent, abaxially densely white tomentose or arachnoid, including the midrib. Capitula 1.5 cm in diameter, radiate, numerous, 3–10(-20), in corymbiform synflorescences, terminal on current-year lateral branches. Peduncles slender, 5–10 mm long. Involucres campanulate or broadly campanulate, 5–6 × 5–7 mm. Phyllaries 4–5-seriate, imbricate, outer phyllaries ovate, ca. 1.2 mm long, narrowly lanceolate, inner phyllaries unequal, lanceolate, 3–4 × ca. 1 mm.

Figure 17. 

Homostylium polium (Schneid.) Z.X.Fu. A. Habit; B. Habitat; C. Capitula (lateral view, showing the involucre); D. Abaxial surface of leaves; E. Capitula; F. Branches of stem (showing capitula terminal on lateral branches). Photographed by Z. X. Fu from Z. X. Fu 2918 (PE).

Endemic to China, Sichuan, Xiaojin (Fig. 18).

Figure 18. 

Distribution of Homostylium polium. China is centrally located on the map.

Shrubland of arid river valleys. 2000–2700 m.

Figure 19. 

Homostylium polium (Schneid.) Z.X.Fu. A. Habit; B. Capitulum; C. Involucral bracts; D. Ray floret; E. Style branches of ray floret; F. Disc floret; G. Style branches of disc floret; H. Stamen of disc floret; I. Pappus bristle. Drawn by Z. J. Chen.

Flowering and Fruiting ca. July to September.

The specific epithet “polium” is derived from the Greek “polios”, meaning “gray” or “hoary”, combined with the Latin neuter suffix “-um”. The name likely refers to the grayish indumentum on the stems or the adaxial leaf surface.

China • Sichuan: Xiaojin, Z. X. Fu 2918 (PE), 2919 (PE), 2920 (PE), 2921 (PE), 2922 (PE), 2923 (PE), 2924 (PE), 2925 (PE), 2927 (PE), E. H. Wilson 2233 (A 00003825, US 01696632).

Xiaojin County is located at the junction of the China-Japan Forest Subregion and the China-Himalayan Plant Subregion, resulting in a diverse vegetation composition. Compared to surrounding areas, the county faces harsh environmental conditions, characterized by water scarcity and aridity. A distinctive feature of the region is the widespread presence of mesophotic, drought-tolerant sparse shrub vegetation. It also underscores the restricted distribution of H. polium. Based on combined ITS and ETS data, Fu et al. (2019) reconstructed a BI phylogenetic tree for Aster, including five Homostylium species. The results showed that H. polium is more closely related to H. argyropholium, compared to H. lavandulifolium. These three species, together with H. albescens and H. fulgidulum, cluster into a monophyletic clade, with H. fulgidulum positioned as the basal species.