Ixeridium

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Description

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.

from: Shih C. & Kilian N. in Wu Z. Y. & al. (ed.), Flora of China 20–21: 328. 2011, Beijing & St Louis.

Distribution

Asia-Temperate: China North-Central (Gansunative: presence questionable, Hebeinative: presence questionable, Shaanxinative: presence questionable, Shandongnative); China South-Central (Chongqingnative, Guizhounative, Hubeinative, Sichuannative, Yunnannative); China Southeast (Anhuinative, Fujiannative, Guangdongnative, Guangxinative, Hunannative, Jiangsunative, Jiangxinative, Zhejiangnative); Hainan (Hainannative); Japan (Hokkaidonative, Honshunative, Kyushunative, Shikokunative); Korea (North Koreanative, South Koreanative); Kuril Is. (Kuril Is.native); Manchuria (Heilongjiangnative: presence questionable, Jilinnative: presence questionable, Liaoningnative: presence questionable); Nansei-shoto (Nansei-shotonative); Taiwan (Taiwannative); Tibet (Tibetnative); Transcaucasus (Adzhariyaintroduced, Azerbaijanintroduced) Asia-Tropical: Assam (Assamnative, Manipurnative, Meghalayanative); Borneo (Sabahnative); Cambodia (Cambodianative); East Himalaya (Arunachal Pradeshnative, Bhutannative, Darjilingnative, Sikkimnative); India (Orissanative, Uttar Pradeshnative, West Bengalnative: presence questionable); Jawa (Jawanative); Laos (Laosnative); Maluku (Malukunative); Myanmar (Myanmarnative); Nepal (Nepalnative); New Guinea (Irian Jayanative, Papua New Guineanative); Philippines (Philippinesnative); Sulawesi (Sulawesinative); Thailand (Thailandnative); Vietnam (Vietnamnative); West Himalaya (Himachal Pradeshnative, Jammu-Kashmirnative, Uttaranchalnative)

Systematics

Ixeridium is a genus of about 15 species, distributed in E and SE Asia. The circumscription of Ixeridium employed here follows Pak & Kawano (1992), based on carpological and karyological investigations, and Shih & Kilian (in Shih & al. 2011), based on molecular phylogenetic analyses of subtribe Crepidinae by J. W. Zhang & al. (in prep.). The placement by the latter authors of the two little-known species with a white pappus, I. aculeolatum and I. sagittarioides is, however, explicitly stated as being tentative, because otherwise the genus only comprises species with a yellowish or straw-coloured pappus. Its basic chromosome number is x = 7. An ITS phylogeny by Nakamura & al. (2014) did not include the critical species with white pappus but otherwise confirmed this concept of Ixeridium, and also showed its sister group relationship to Ixeris.

References

Nakamura K., Chung S.-W., Kono Y., Ho M.-J., Hsu T.-C. & Peng C.-I 2014: Ixeridium calcicola (Compositae), a new limestone endemic from Taiwan, with notes on its atypical basic chromosome number, phylogenetic affinities, and a limestone refugium hypothesis. \u2013 PLoS ONE 9(10): e109797. // ➪//

Pak J.-H. & Kawano S. 1992: Biosystematic studies on the genus Ixeris and its allied genera (Compositae: Lactuceae): 4. Taxonomic treatments and nomenclature. – Mem. Fac. Sci. Kyoto Univ., Ser. Biol. 15: 29–61.

Shih C., Ge X. J.; Kilian N., Kirschner J., Štěpánek J., Sukhorukov A. P., Mavrodiev E. V. & Gottschlich G. 2011: Cichorieae. – Pp. 195–353 in: Wu Z. Y., Raven P. H. & Hong D. Y. (ed.), Flora of China 20–21. Asteraceae. – Beijing: Science Press & St Louis: Missouri Botanical Garden.

Common names

Chinese (China): 小苦荬属 xiao ku mai shu A

Chromosome numbers

Diploids, triploids and tetraploids, x = 7.B

Bibliography

A. Wu & al., Flora of China 20-21. 2011
B. Watanabe K., Index to chromosome numbers in Asteraceae.