Herbs or subshrubs, perennial, slightly woody at base. Leaves alternate. Inflorescences terminal or axillary, virgate, spikelike racemes, 8-30-flowered. Flowers: sepals 4; stamens 4-8; carpels 1; ovary 1-loculed; style absent; stigma 1. Fruits achenes, elongate-cuneate, apically 2-lobed, each lobe tipped with 1-3 sharply reflexed spines 3-5 mm. Seed 1.