Homostylium albescens (DC.) Z. X. Fu, 2025

Chen, Xinyu & Fu, Zhixi, 2025, Resurrection of the genus Homostylium Nees for the former Aster ser. Albescentes Y. Ling (Astereae, Asteraceae), with an updated generic synopsis, PhytoKeys 259, pp. 27-66 : 27-66

1. Homostylium albescens (DC.) Z. X. Fu comb. nov.

Figs 2 , 3

≡ Amphirhapis albescens DC. , Prodr. 5: 343. 1836. ≡ Microglossa albescens (DC.) C. B. Clarke , Compos. Ind. 59. 1876. ≡ Aster albescens (DC.) Wall. ex Hand. - Mazz. , Acti Horti Gothob. 12: 205. 1938. ≡ Sinosidus albescens (DC.) G. L. Nesom , Phytoneuron 2020-64: 12. 2020. Type: Nepal, Kamaon, Gossain-Than, N. Wallich 2974 / 84 (lectotype, designated by Nesom (2020 g), K 001118307!) (Suppl. material 1: fig. S 1).

= Aster cabulicus Lindl. , Edwards’s Bot. Reg. 29: 62, no. 89. 1843. ≡ Homostylium cabulicum (Lindl.) Nees , Del. Sem. Hort. Bot. Vratisl. 3. 1844. ≡ Microglossa cabulica (Lindl.) C. B. Clarke , Compos. Ind. 57. 1876. Type: Typified by the description.

= Aster ignoratus Kunth et Bouche , Ind. Sem. Hort. Berol. 11. 1845. Type: Unknown place, Herb, Schultz Bip. 81 (holotype, P 00691946!) (Suppl. material 1: fig. S 2).

= Aster ferrugineus Edgew. , Trans. Linn. Soc. 20: 64. 1846. Type: India, Carhoul State, Mana. M. P. Edgeworth 16 (holotype, K 000890396!) (Suppl. material 1: fig. S 3).

= Microglossa salicifolia Diels , Bot. Jahrb. Syst. 29: 612. 1901. Type: China, Chongqing, Leijiaping, A. V. Rosthorn 136 (holotype, B, not seen).

= Aster cavaleriei Vaniot & H. Lév. , Bull. Soc. Bot. France 53: 549. 1906. Type: China, Guizhou, Tien-sen-kiao river, Novomeber 1904, J. Cavalerie 1895 (holotype, E, not seen).

Type.

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

Description.

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.

Distribution.

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 ).

Habitat.

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.

Phenology.

Flowering June to September. Fruiting August to October.

Etymology.

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.

Notes.

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.

Figures

Figure 2. Homostylium albescens (DC.) Z. X. Fu. A. Flowering plant; B. Abaxial surface of leaf. Photographed by Z. X. Fu.

Figure 3. Distribution of Homostylium albescens. China is centrally located on the map.