Description

Key Characters:

Growth Form: Herbaceous, rooted, submerged to emergent plant.

Stems: Stems prostrate to ascending or erect, often rooting at the lower nodes, 2–5 dm long, unbranched or branched.

Roots:

Leaves: Leaves simple. Leaves in whorls of 3–6 per node. Blades 2–3,5 cm long, with 8–15 linear segments 3–8 mm long on each side of the midrib. Margins entire, toothed, or deeply dissected. Petioles to 9.6 mm long. Stipules absent.

Flowers: Flowers sessile, usually in the axils of the upper, reduced leaves, usually above the surface of the water, each flower often subtended by persistent or deciduous bracteoles. Flowers unisexual, uppermost usually staminate, lower ones pistillate. Calyx of saminate flowers (2)4-lobed, Calyx of pistillate flowers 4-toothed, ca. 1 mm long. Corolla of staminate flowers with petals (0)2–4; pistillate flowers with corolla (petals) absent. Stamens in staminate flowers 2, 4, or 8; anthers tetrathecal, opening by slits. Ovary inferior (pistillate flowers), 4-celled; ovules anatropous, pendulous from apex; styles as many as sepals, rarely half as many, feathery; stigmas 4, recurved and plumose.

Fruit: Fruit ca. 3 mm long; separating into 4 nut-like segments at maturity; these sometimes tuberculate on the back; the sepals persistent on the fruit; erect or reflexed. Seeds 1–4; endosperm copious; fleshy and oily.

Ploidy:

Habitat: Naturalized in permanent standing or running water; especially in taro paddies and pastures.

Elevation Range: 0–1,280 m.