Description

Key Characters:

Growth Form: Annual or perennial herbs.

Stems: Stems red, ascending, swollen and often rooting at the nodes, 5–15 dm long, glabrous.

Roots:

Leaves: Leaves simple. Alternate. Blades oblong–lanceolate to narrowly lanceolate, (10–)14–28 cm long, (2–)3–6 cm wide. Surfaces minutely pustulate, otherwise usually glabrous, sometimes with scattered hairs on nerves of lower surface. Margins entire. Petioles 0.5–2 cm long. Stipules present as an ocreae, tubular, usually 20–30 mm long, apex not ciliate, sometimes with a few small bristles ca. 0.5 mm long.

Flowers: Flowers in open racemes, these sometimes in paniculate inflorescences 5–10 cm long, each flower on a jointed pedicel. Flowers bisexual (perfect), actinomorphic. Tepals (4)5(6), usually petaloid, persistent, white or pinkish, 3–4 mm long, sometimes sparsely so, glandular punctate. Stamens 3–9, but usually 5, exserted or included; anthers dithecal, opening by longitudinal slits. Ovary superior, (2)3(4)-carpellate, 1-celled; ovule 1; styles 2–3, distinct or connate basally, deciduous; stigmas capitate or rarely fimbriate, dry.

Fruit: Nuts dark brown to nearly black; broadly ovoid; biconvex or subtrigonous; protruding up to ca. ½ its length from or completely enclosed by the persistent tepals; 2–2.5 mm long; the surface glossy.

Ploidy: 2n = 20; 40; 60; 66

Habitat: Along streambeds; taro paddies; or in moving water.

Elevation Range: 260–1,450 m.