247. Centipeda Loureiro, Fl. Cochinch. 2: 492. 1790.
石胡荽属 shi hu sui shu
Authors: Zhu Shi & Michael G. Gilbert
Annual or perennial herbs. Leaves alternate, entire or coarsely toothed. Capitula apparently axillary, solitary or in monochasial cymes, sometimes grouped into racemelike synflorescence, sessile or shortly pedunculate, heterogamous and discoid. Involucre small, hemispheric; phyllaries in 1 or 2 series, subequal, herbaceous, margins scarious. Receptacle flat or convex, naked. Marginal florets female, in several rows, fertile; corolla minute, tubular, obscurely 3-lobed, creamy white, pale yellow, green, or purplish. Disk florets few, bisexual; corolla campanulate, 4-lobed, similar in color, glabrous. Anthers obtuse at base. Style branches of disk florets short, truncate. Achenes scarcely compressed, obtusely 3- or 4-ribbed or -angled; corona absent.
Ten species: all species in Australia and New Zealand, one species extending to South America, one species extending to Papua New Guinea, and one weedy species extending to Asia and the Pacific Islands, including China.
GENERA INCERTAE SEDIS
Centipeda superficially resembles Cotula in the Anthemideae, where it was placed in the treatment in FRPS (76(1): 132-133. 1983), but it differs in the synflorescence and in the tubular corollas of the female florets. K. Bremer and Humphries (Bull. Nat. Hist. Mus. London, Bot. 23: 161. 1993) suggested that it be placed in the Astereae, whereas N. G. Walsh (Muelleria 15: 33. 2001), in his revision of the genus, suggested that it might belong to the Astereae or Gnaphalieae. Panero (in Kadereit & C. Jeffrey, Fam. Gen. Vasc. Pl. 8: 399. 2007) placed it in its own subtribe within the Athroismeae on the basis of molecular data.