Erect annual herb to 1 m tall, sparsely branched; stems yellowish-green to brown, terete, finely striate, glabrescent. Leaves mostly opposite, alternate above; blades membranaceous, broadly rhombic-ovate, to 3.7 cm long and 3.0 cm wide, the margins crenulate, the apex short-acute, the upper surface with sparse coarse hairs, the lower surface with glandular punctations, with puberulous veins, the veins prominently trinervate at the base; petioles slender, to 2.5 cm long. Inflores-cence a lax panicle with loosely cymose branches, the ultimate branches 2-7 mm long, slender, puberulous. Heads ca. 4 mm high with 20-35 florets; involucral bracts 15-22, subimbricate, unequal, in ca. 3 series, mostly bicostate, the outer 2 series usually narrowly acute, sparsely short-hirsute, the 2nd series with hairs only along the median line, the inner bracts broad and mostly scarious at the tip, often with a short mucro; corolla lavender or white, ca. 2 mm long, without hairs on lobes; style branches thick. Achenes scarcely constricted above, usually with yellow ribs and blackish sides, the ribs and upper lateral surfaces usually scabrid; pappus of 25-30 slender scarcely contiguous bristles. Chromosome number n = 4.
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