Shrubs, subshrubs, or herbs, sometimes nearly arborescent, perennial, biennial, or annual, polycarpic or, rarely, monocarpic (subg. Pterogonum), synoecious (sometimes polygamodioecious in subg. Micrantha and Oligogonum, rarely dioecious in subg. Oligogonum); taproot slender to stout, solid, or rarely chambered (subg. Pterogonum). Stems prostrate or decumbent to erect, infrequently absent, glabrous or pubescent, sometimes glandular; caudex stems absent or woody, tightly compact to spreading and at or just below surface, or spreading to erect and above surface; aerial flowering stems arising at nodes of caudex branches, at distal nodes of aerial branches, or directly from the root, prostrate or decumbent to erect, slender to stout, solid or slightly to distinctly hollow and fistulose, rarely disarticulating into ringlike segments (subg. Clastomyelon). Leaves usually persistent through anthesis, occasionally persistent through growing season or longer, sometimes marcescent or quickly deciduous, basal and sometimes sheathing up stems, cauline, or basal and cauline, alternate, opposite, or whorled, 1 per node or fasciculate; petiole usually present, sometimes obscure; blade linear to orbiculate, entire apically. Inflorescences terminal or terminal and axillary, cymose and dichotomously or trichotomously branched, or racemose, simple or compound-umbellate, subcapitate, or capitate, occasionally distally uniparous due to suppression of secondary branches; branches mostly dichotomous except for initial trichotomous node, not brittle or disarticulating into segments, round and smooth, rarely grooved, angled or ridged, variously lanate, tomentose, floccose, sericeous, hispid, pilose-pubescent, or puberulent, occasionally glandular, rarely scabrellous; bracts 2-13 or more at proximal nodes, usually 3 distally, connate proximally, leaflike, semileaflike, or scalelike, not awn-tipped, glabrous or variously pubescent or glandular. Peduncles absent or erect to deflexed. Involucres 1-8 or more per cluster, smooth or ribbed, tubular, cylindric or narrowly turbinate to broadly campanulate or hemispheric; teeth 5-10, sometimes lobelike, not awned. Flowers bisexual or, infrequently, unisexual, (2-)6-100 per involucre at any single time during full anthesis, sometimes with stipelike base; perianth usually white to red or variously yellow, broadly campanulate when open, cylindric to urce
This project was made possible in part by the Institute of Museum and Library Services [MG-70-19-0057-19].