Crepidiastrum Genus

Crepidiastrum is a genus of flowering plants in the daisy family Asteraceae (order Asterales), described by the Japanese botanist Takenoshin Nakai in 1920 (Botanical Magazine, Tokyo 34: 147), with Crepidiastrum lanceolatum as the type species. Flora of China recognizes about 15 species in the genus, native to central and eastern Asia — including China, the Korean peninsula, and Japan, where its range extends to the Bonin (Ogasawara) Islands in the North Pacific. Broader treatments, reflected in GBIF/WCVP data, extend this footprint further west and south, into Siberia, Mongolia, the Himalaya, parts of Central Asia (Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan), Taiwan, Vietnam and the Philippines.

Members are annual, biennial, or perennial herbs, occasionally subshrubs, often forming leafy or basal rosettes from a taproot. Leaves are undivided or pinnately lobed, and the stem leaves are sometimes clasping. The narrow, cylindrical flower heads carry 5 to 20 yellow florets, and the fruit is a slightly flattened, spindle-shaped achene with five main ribs, usually roughened by small forward-pointing hairs, tipped with a whitish, easily shed pappus. The genus's basic chromosome number is x = 5.

Generic boundaries have shifted with taxonomic research. Paraixeris Nakai is now treated as a synonym of Crepidiastrum, following carpological and cytological work by Pak and Kawano (1992) that was later corroborated by molecular phylogenetic studies. A related genus, Crepidifolium, was originally described as a segregate of Youngia but was found to nest within the Crepidiastrum clade; some floras, including Flora of China, still treat it as a congener, which is why certain circumscriptions of Crepidiastrum extend as far as Central Asia. Other historical synonyms include ×Crepidiastrixeris Kitam. and Geblera Kitag.