Cyanthillium is a small genus of tropical flowering plants in the daisy family, Asteraceae, placed within the tribe Vernonieae. It was described by the German-Dutch botanist Carl Ludwig Blume in 1826, in Bijdrage tot de Flora van Nederlandsch Indië. GBIF's backbone taxonomy places the genus in the family Asteraceae and order Asterales, within class Magnoliopsida (dicotyledons).
The genus comprises about a dozen accepted species, most of which are low, weedy herbs found across the tropics and subtropics of Africa, Asia, Australia, and the Pacific. Several species have restricted native ranges — for example, Cyanthillium albicans and C. conyzoides are known from southwestern India, C. hookerianum from Sri Lanka, C. maritimum from the Philippines and Taiwan, and C. polytrichomata from Tanzania and Zambia — while others are more widespread. The best-known member, Cyanthillium cinereum, occurs naturally across tropical Asia and tropical Africa and has become naturalized well beyond its native range, including in the tropical Americas and Florida, where it grows as a common roadside and waste-ground weed.
Like many Vernonieae, species in this genus typically bear small, clustered heads of purple to lavender disc florets rather than the showy ray florets seen in some other Asteraceae.
Distribution
Cyanthillium species are native to tropical and subtropical Africa, Asia, Australia, and the Pacific. Individual species often have narrow native ranges (e.g. southwestern India, Sri Lanka, the Philippines/Taiwan, or parts of tropical Africa), while Cyanthillium cinereum has become widely naturalized outside its native tropical Asian/African range, including in the tropical Americas and Florida.
Taxonomy Notes
Cyanthillium was published by Blume in 1826 (Bijdrage tot de Flora van Nederlandsch Indië, p. 889) and is placed in the tribe Vernonieae within the family Asteraceae (order Asterales). GBIF's backbone recognizes it as an accepted genus; Wikipedia lists 12 accepted species.
