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Rays pistillate and fertile, yellow, inconspicuous, commonly solitary, or sometimes wanting; invol of 2–8 subequal greenish bracts, occasionally with 1 or 2 smaller outer ones; receptacle small, naked or sometimes bristly; disk-fls 1–15, perfect and fertile, yellow; style-branches flattened, truncate, minutely penicillate; achenes glabrous, ca 10-ribbed; pappus wanting, or of 2–4 irregular scales; herbs with narrow, opposite, sessile and often connate lvs, and numerous small, sessile or subsessile glomerate heads. 20, New World.
Annual or perennial herbs or shrubs. Leaves opposite, with connate leaf bases, 3-veined from base. Capitula in terminal or axillary dense cymes or glomerules, heterogamous or much reduced to a single floret; phyllaries in several rows; receptacle epaleate. Corolla with female ray floret, or only one ray on the outside of the outer capitulum, and hermaphrodite disc florets.. Anther appendage narrowly ovate. Achenes black, narrowly obovoid; pappus absent or rarely of a few scales.
