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FOC | Family List | FOC Vol. 20-21 | Asteraceae

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.

1 Pappus white   (2)
+ Pappus yellowish or straw-colored   (3)
2 (1) Rosette leaves oblanceolate, lyrately lobed; leaf blade attenuate into a petiole much shorter than blade; stems and branches very sparsely white echinulate.   7 I. aculeolatum
+ Rosette leaves triangular or pentagonal, pinnately lobed; leaf blade contracted into a winged petiole longer than blade; stems and branches glabrous and smooth.   8 I. sagittarioides
3 (1) Inner phyllaries (7 or)8; florets 8-11   (4)
+ Inner phyllaries 5; florets 5-8   (5)
4 (3) Basal leaves narrowly spatulate to almost linear, undivided, margin entire.   1 I. gracile
+ Basal leaves narrowly elliptic to linear-elliptic, undivided or more rarely pinnatipartite, margin denticulate, sinuate-dentate, or more rarely entire.   2 I. laevigatum
5 (3) Involucre 4.5-6.5 mm   (6)
+ Involucre 7-8 mm   (7)
6 (5) Plants 20-80 cm tall; basal leaves crowded, 5-17 cm; pappus 2.5-3 mm.   3 I. beauverdianum
+ Plants only to 15 cm tall; basal leaves in a rosette, 2-4 cm; pappus ca. 4 mm.   4 I. yunnanense
7 (5) Herbs 20-50 cm tall; stems slender; basal leaves oblanceolate to elliptic, 1-3 cm wide; stem leaves lanceolate, basally widened, usually clasping.   5 I. dentatum
+ Herbs 10-20 cm tall; stems delicate; basal leaves narrowly elliptic to linear-elliptic, less than 1 cm wide; stem leaves (if any) linear-elliptic, basally attenuate, never clasping.   6 I. transnokoense

Lower Taxa


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