Description from Flora of China
Crepidifolium Sennikov; Geblera Kitagawa (1937), not Fischer & C. A. Meyer (1835); Paraixeris Nakai.
Herbs, annual, biennial, or perennial, sometimes subshrubs, often rosulate, with a taproot. Stems usually leafy. Leaves undivided or pinnately lobed; stem leaves often clasping. Capitula with 5-20 florets. Involucres narrowly cylindric. Phyllaries with narrow scarious margin; outer phyllaries few, longest ca. 1/4(-1/2) as long as inner ones; inner phyllaries 5 or 8, linear-lanceolate, equal in length. Receptacle naked. Florets yellow. Achene ± fusiform, slightly compressed, with 5 main ribs alternating with 1 or 2 secondary ribs, usually scabrid of antrorse acute papillae especially toward apex, rarely glabrous or muriculate, apex attenuate or with a beak less than 1/5 or to 1/2 of achene length. Pappus white, scabrid, usually ± caducous.
Crepidiastrum, in the circumscription used here, includes Paraixeris, following the conclusions by Pak and Kawano (Mem. Fac. Sci. Kyoto Univ., Ser. Biol. 15: 29-61. 1992) of their carpological and cytological investigations, which have been corroborated through recent molecular phylogenetic analyses by J. W. Zhang et al. (in prep.). The analyses by J. W. Zhang et al., moreover, revealed that the Youngia segregate Crepidifolium is also nested within the Crepidiastrum clade, thus confirming an earlier assumption by Sennikov (Bot. Zhurn. 82(5): 113-116. 1997), which Sennikov later revised in favor of establishing the separate genus Crepidifolium (Sennikov & I. D. Illarionova, Komarovia 5: 96. 2008). This genus is therefore also treated here as a congener of Crepidiastrum, extending its geographical range to C Asia. Its basic chromosome number is x = 5.
About 15 species: C and E Asia, including N Pacific Bonin (Ogasawara) Islands; nine species (two endemic) in China.
(Authors: Shi Zhu (石铸 Shih Chu); Norbert Kilian)