Annual or biennial, glabrous, up to 70 cm., turning yellowish-green with age. Stems erect, simple below, paniculate above, sulcate-striate. Leaves up to 13 x 3 cm., petiolate, oblong-lanceolate to lanceolate-linear, more or less tapering at base, acute at apex, minutely crisp. Whorls many-flowered, the lowest more or less remote, the upper crowded, all subtended by narrow leaves. Pedicels mostly longer than valves, filiform, jointed near base, elongated in fruit, reflexed. Outer tepals usually spreading, sometimes subrecurved in fruit. Valves 2.5-4 mm., narrowly ovate-triangular, somewhat acute, with 2 narrow, 1.5-2.5 mm. long teeth on each side, reticulate-veined, each valve bearing a prominent, yellowish, lanceolate, about 1 .5 mm. long wart. Achene 1.3-1.5 mm., trigonous, ovoid, acuminate, yellowish-brown. F1. April.