Herbs annual, all parts densely pubescent, gray-white hirsute. Tap root slender. Stem thinly ribbed, branched. Leaves pinnate (rarely 2-pinnate/pinnatifid); petioles with narrow membranous sheath; pinnae narrowly oblong, coarsely dentate, sessile, the terminal decurrent at base. Umbels terminal and lateral; rays few, lax; bracts and bracteoles present. Flowers polygamous; outer flowers of umbellules bisexual, inner staminate. Calyx teeth subulate-lanceolate, prominent. Petals purple-red to pinkish white, obovate, the outer enlarged (radiant) obreniform, apex notched, with narrow inflexed lobe. Stylopodium conic; styles short. Fruit ovoid, flattened laterally, densely covered with prickles or bristles; primary and secondary ribs evident, primary ribs bearing 3 rows of bristles, the secondary ribs 1 row of bristles; vittae 1 in each furrow (under each secondary rib) and often 2 under each primary rib, 2 on commissure. Seed face involute with deeply incurved lateral margins. Carpophore bifid at apex.