Erect, monopodial, annual herb, 0.5-0.8 m tall. Stems herbaceous, purple-blotched, not branched at base, simple or slightly dichotomously branched higher up; branches ascending to erect, not sprouting from nodes. Leaves 40-120 x 25-50 mm, 2-pinnate, coriaceous; ultimate leaflet segments linear-oblong, 3-10x<0.5mm, laminate to subterete, concolorous, green, margins entire, venation visible or obscure. Petioles 15-40 mm long, glabrous, purple-blotched. Umbels with peduncle short to long, 15-60 mm long; involucral bracts 4 to 6, lanceolate, coriaceous, acuminate, margins membranous, glabrous; rays (6)10 to 18, 15-35 mm long, scabrid; involucel bracts 4 to 6, linear to lanceolate, coriaceous, acuminate, margins membranous, glabrous; raylets 6 to 14, 4-8 mm long, scabrid. Flowers with petals 0.8-1.0 mm x 0.6-1.0 mm, deeply emarginate, papillose; ovary scabrid; styles usually lengthening as fruit matures, 0.7-1.4 mm long, becoming reflexed and extending well beyond base of stylopodium. Fruit 4.0-6.0 x 3 mm, elliptic in lateral view, base obtuse; mericarps homomorphic; median and lateral ribs as well developed as marginal ribs, prominent, cartilaginous, dorsal surface with fibrous ridges, glabrous; marginal ribs parallel to very slightly concave in lateral view.
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Like D. hispidum but plants to 80 cm, stem with purple blotches, involucral and involucel bracts never foliose and fruit > 4 mm long.