73. Ixeridium (A. Gray) Tzvelev, Fl. URSS. 29: 388. 1964.
小苦荬属 xiao ku mai shu
Authors: Zhu Shi & Norbert Kilian
Ixeris [unranked] Ixeridium A. Gray, Mem. Amer. Acad. Arts, n.s., 6: 397. 1858.
Herbs, perennial, often rosulate. Stem ascending-erect to erect, branched from base or higher up. Synflorescence usually corymbiform or paniculately corymbiform, with few to many capitula. Capitula with 5-11(-18?) florets. Involucre narrowly cylindric. Phyllaries in few series, margin narrow and scarious; outer phyllaries few, very short (at most ca. 2 mm, usually less), ± unequal; inner phyllaries 5 or (7 or)8, linear-lanceolate, equal. Receptacle naked. Florets some shade of yellow [or rarely white]. Achene pale brown to brown, usually ± subfusiform, subcompressed, with 5 slender main ribs alternating usually with 1 (only exceptionally with 0 or 2) narrower to subequal secondary ribs, space between ribs widely U-shaped, apically often with antrorse acute papillae, apex attenuate into a short slender beak. Pappus yellowish to straw-colored or rarely ?white, of scabrid bristles.
About 15 species: E and SE Asia; eight species (three endemic) in China.
The revised circumscription of Ixeridium employed here basically follows the treatment by Pak and Kawano (Mem. Fac. Sci. Kyoto Univ., Ser. Biol. 15: 29-61. 1992), based on carpological and karyological investigations, which has been corroborated recently in molecular phylogenetic analyses of subtribe Crepidinae by J. W. Zhang et al. (in prep.). The placement of the two little-known species with a white pappus is, however, tentative; otherwise, the genus only comprises species with a yellowish or straw-colored pappus. Its basic chromosome number is x = 7.
