Stems simple or branched, nodes more than 2. Leaves cauline. Inflorescences opposite leaves and/or terminal, racemes, lax, spikelike, not subtended by petaloid bracts. Flowers 175-350, not coalescent; stamens (3-)6(-8), hypogynous or epigynous; pistil 1, (3-)4-5(-7)-carpellate, connate only at base; placentation marginal; ovules 2 per placenta (only 1 developing into seed). Fruits schizocarps; mericarps dry, indehiscent. Seed 1 per mericarp. x = 11.
Stamens 6-8; carpels united at the base only, each with a short, outcurved style, stigmatic along the inner side; fr subglobose, indehiscent, strongly rugose; herbs with jointed stems, broad, alternate lvs, and white fls in slender spikes. 2, the other Asian.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.