Coarse usually woody, sparingly branched vines; stems pale to dark brownish, terete, striate, slightly puberulous to sparsely hirsute, the larger stems often fistulose. Leaves opposite; blades usually ovate to broadly ovate, sometimes with prominent angles, to 15 cm long and 10 cm wide, the base rounded, the margins entire, the apex short-acute to slightly acuminate, the upper surface sparsely puberulous to glabrate, the lower surface brownish puberulous, glandular puncta-tions not prominent, the venation with two pairs of prominent secondary veins in the basal quarter, the upper pair strongly ascending and giving a trinervate aspect, the tertiary veins not prominently and regularly transverse; petioles sometimes slender, 1-5 cm long. Inflorescence a panicle with paniculate branches, the branches puberulous; heads in pairs or groups of 3 congested near tips of short branches, sessile. Heads 8-9 mm high; subinvolucral bract 1.5-2.0 mm long, thin with few or no hairs abaxially; involucral bracts oblong with rounded tips, ca. 4 mm long including the somewhat swollen bases, ca. 1 mm wide, somewhat puberulous and glandular-punctate on outer surface; corolla whitish, fragrant, 4.5-5.5 mm long, the tube distinct, 1.0-1.5 mm long, the limb narrowly campanulate, the lobes half again as long as wide with a few glands and short hairs near the tips, the cells oblong, 15-25 u wide, the cell walls slightly sinuous; anther appendages firm, ovate-triangular, slightly longer than wide; style base glabrous, the style appendages with short papillae. Achenes with 4-5 ribs, ca. 3.5 mm long, the sides with a few short hairs and glands; pappus of 40-50 slender, sometimes sharply angled, bristles mostly in 1 series, the tips not or scarcely enlarged, the apical cells often acute.
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