Erect, +/- glabrous herb, usually to 1 m tall, branched; stems usually 4-winged. Blades subsessile, lanceolate to linear, attenuate to apex, +/- acute at base, mostly 5-12 cm long, 1-3.5 cm wide, prominent lateral veins in 11-16 pairs, conspicuously loop-connected. Flowers solitary in upper axils, 4-parted; sepals lanceolate-ovate, 7-10 mm long; petals yellow, 8-12 mm long; stamens 8, 2-3 mm long; style ca 2 mm long; stigma globose, ca 2 mm thick. Capsules clavate-obpyramidal, (8) 12-20 mm long, 4-angled or 4-winged, the corners dark-ribbed, weathering into fibers; seeds subcylindrical, less than 1 mm long, free, multiseriate in each locule, the raphe ca one-fifth the width of the body. Bailey & Bailey 384.