Outer fls of the head pistillate, with short and inconspicuous, 2-3- toothed, radiate or subcampanulate, whitish or yellowish cor, the inner fls perfect, tubular, regularly 3-5-toothed; invol biseriate and dimorphic, the outer series of ca 5 linear-oblanceolate, spreading or reflexed green bracts, the inner shorter and broader, erect, each subtending a pistillate fl; receptacle very small, its membranous bracts concave and clasping the achenes; style-branches flattened, with short, hairy appendage; achenes quadrangular, incurved, glabrous; pappus none; branching, mostly annual, ±glandular herbs with opposite, toothed lvs and small heads. 6, mainly warm reg.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.