Leafl. W. Bot. 8: 26. 1956.
Annuals, mostly 10–100 cm (taprooted). Stems erect, branched distally, stipitate-glandular (at least distally). Leaves cauline (at flowering); alternate; sessile or petiolate (bases of blades ± decurrent onto petioles); blades 1(–3+)-nerved, oblanceolate to linear (sessile, smaller, bractlike distally), margins entire or nearly so, faces stipitate-glandular. Heads radiate, borne singly or in open, corymbiform to paniculiform arrays. Involucres ± campanulate to turbinate or fusiform, (8–10 ×) 3–5 mm. Phyllaries 22–35+ in (4–)5–6+ series, 1-nerved (flat), lanceolate to linear, unequal, herbaceous to ± cartilaginous, margins scarious, apices (slightly spreading to nearly squarrose) some or all bearing a tack-shaped gland. Receptacles flat, pitted, epaleate. Ray florets 5–8(–13+), pistillate, fertile; corollas yellow (occasionally suffused with red, becoming revolute). Disc florets 9–20+, functionally staminate; corollas yellow, tubes about equaling funnelform to campanulate throats, lobes 5, erect, lance-deltate; style-branch appendages lanceolate. Cypselae (mottled purple-brown) ± plumply clavate, ± triquetrous, 3-nerved, faces sericeous; pappi readily falling (fragile), of 2–8 whitish, subulate, barbellate scales (flattened bristles) in 1 series. x = 5.