Erect, annual herb with up to 1.5 m tall, sparsely puberulous, striate, red-tinged, simple stem. Basal and lower stem leaves long petiolate, ovate, 3-pinnatisect, 3 – 10 x 2 – 5 cm, primary segments remote, oblong,, pinnatisect or pinnatipartite, secondary segments pinnatifid into lanceolate, 1 – 5 x 0.5 – 1 mm, acute, entire or toothed lobules; upper and mid stem leaves subsessile or sessile, (1-) bipinnatisect, basally auriculate, uppermost in floral region lanceolate, dentate or linear and entire. Capitula heterogamous, pedunculate, numerous, hemispherical, remote, 1.5 – 2 x 2 – 3 mm, nodding in lax, 10 – 50 x 5 – 20 cm, terminal panicle with oblique or patent branches. Involucre 3-seriate, phyllaries glabrous, shining; outermost linear-oblong, green with narrow scarious margins, inner oblong-ovate or broadly ovate-elliptic, with broad scarious margins. Receptacle conical, glabrous. Florets up 30, greenish-yellow, all fertile; marginal florets 5-10, with irregularly 2-toothed, filiform, glandulose corolla tube; disc-florets 5-20, bisexual, with broadly tubular, 5-dentate, c. 1 mm long corolla. Cypselas narrowly oblanceolate, 0.6 – 0.8 mm long, brown.