Annual herbs with tap root, sometimes rooting from lower prostrate stems; stems erect or semiprostrate. Leaves simple, opposite, petiolate, ovate to trullate, weakly crenate, 3-veined; base attenuate. Capitula 1–several in terminal clusters, sessile or subsessile, discoid; involucral bracts 4 or 5 in 2 or 3 series, ovate, herbaceous, with innermost bracts scarious (actually empty paleae through loss of ray florets); receptacle paleate; paleae keeled, linear, acuminate, scarious, pilose, semi-embracing achenes. Florets few, usually 5 or 6, bisexual, fertile; corolla 5-merous, yellow; anther sacs black or golden brown Achenes narrowly obovoid, somewhat compressed, subangular, not winged, narrowed to a small cylindric boss or rostrum apically. Pappus absent.
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