Dichrocephala is a small genus of annual herbs in the daisy family, Asteraceae, within the order Asterales. It was described by Charles Louis L'Héritier de Brutelle (completed by Augustin Pyramus de Candolle) and published in 1833. The genus comprises only about four accepted species, native to tropical and southern Africa (including Madagascar) and tropical Asia; three of the four species are found in China, where the genus is known as 鱼眼草属 ("fish-eye-grass genus").
Plants in the genus are low, prostrate annual herbs with alternate leaves that are either entire or lyrate (lobed, with a large terminal lobe). Their flower heads (capitula) are small, disc-shaped (disciform), and orbicular to oblong, typically arranged in raceme- or panicle-like clusters rather than borne singly. The involucre is shallow and saucer-shaped, with phyllaries (bracts) in two or three overlapping series, each with narrow, papery, fringed margins. The receptacle bearing the florets is swollen and pitted (alveolate) but lacks scales, and is either globose or obconic in shape.
Each head carries many small, tubeless marginal female florets — white or yellow, and variable in shape from narrowly cylindric to funnel-shaped, bell-shaped, or urn-like, with 2 or 3 lobes — surrounding a center of bisexual disk florets that are yellow or reddish with 4 or 5 lobes. The fruits are small, flattened, glabrous achenes, sometimes glandular near the base and tip, and generally lack a true pappus, though disk-floret achenes may bear a low crown-like rim or one or two short bristles.
The best-known and most widespread member is Dichrocephala integrifolia, which — unusually for such a small genus — has an extensive native distribution spanning tropical and southern Africa, Madagascar, the Arabian Peninsula, Turkey, the Caucasus and Iran, China and Southeast Asia, New Guinea, Australia, and several Pacific islands including Hawaii. The genus as a whole is centered on the Old World tropics and subtropics.
Distribution
Dichrocephala is native to the Old World tropics and subtropics, centered on Africa and tropical Asia. Of its four species, three occur in China. The most widespread species, Dichrocephala integrifolia, ranges from tropical and southern Africa and Madagascar through the Arabian Peninsula, Turkey, the Caucasus, and Iran to China, Southeast Asia, New Guinea, Australia, and parts of the Pacific (including Hawaii).
Taxonomy Notes
The genus was described by L'Héritier ex de Candolle and published in 1833 (Archiv. Bot. (Paris) 2: 517). It sits in the daisy family Asteraceae, order Asterales, and comprises only about four accepted species. In China it is known as 鱼眼草属 (yú yǎn cǎo shǔ, "fish-eye-grass genus").
