Stout annual herb up to 80-(100) cm high. Stems glabrous, usually simple or sometimes somewhat branched at base. Stem lvs always alternate, glabrous, lanceolate to linear, usually obovate or oblong at base of stem, acuminate, 3-nerved, entire, (5)-10-40 mm long; lvs subtending infl.-branches single, similar to stem lvs but usually somewhat smaller. Infl. of few to numerous fls in a diffuse compound dichasium or corymb; sepals elliptic to suborbicular, acuminate, (5)-6-10 mm long, < capsule, with glabrous entire margins; petals white or pale to dark blue, 2-3× as long as sepals, (10)-12-18-(20) mm long; styles united for c. ⅓ length. Capsule glabrous, subglobose, indehiscent or subdehiscent, (6)-8-10-(12) mm diam.; seeds elliptic and narrowed to base, shiny light to dark brown, 4-5 mm long.