Branched annual herb, up to 1.5 m tall. Stems hollow. Leaves lanceolate, narrowly ovate to elliptic, up to 12 × 5 cm, hairless; margin entire; petiole up to 1.5 cm long. Flowers in conical-cylindric spikes, up to 12 cm long. Corolla very small, white, greenish or pink yellow. Fruit a capsule, 4-5 mm in diameter, dehiscing below the calyx lobes, leaving the base attached to the rhachis.