Glabrous, erect annual. Stems up to 35-(40) cm high, branched or not from base. Lvs alternate, exstipulate, sessile, entire, linear, obtuse at base, acuminate, 15-40 mm long. Terminal umbel usually 5-rayed, with often several axillary rays arising below; lvs subtending rays linear to narrowly ovate-elliptic; rays sometimes secondarily branched then forming conspicuous yellow, compound dichasia; lvs subtending ray-branches and cyathia deltate, obtuse. Glands elliptic-oblong; horns long, slender. Capsule smooth, deeply grooved, granulate on keels. Seeds rounded, with numerous irregular shallow pits, grey on ridges and brown in pits, 1.5-2 mm long.