Description

Key Characters:

Growth Form: Fronds free–floating on water surface, solitary or usually cohering in colonies of 2–5.

Stems: Both surfaces green, obovate to suborbicular, +/- symmetrical, flat to slightly convex on both surfaces, not inflated, 1–5 mm long, 0.7–3 mm wide, +/- obscurely 1–3–nerved, root sheath winged.

Roots:

Leaves: Leaves absent. Alternate. Stipules absent.

Flowers: Flowers borne in a pouch, 2 staminate and 1 pistillate, enclosed in a membranous sheath in a marginal cleft of the frond, opening along the side or nearly closed. Flowers unisexual, 1(--2) per frond, surrounded by small utricular, membranous scale. Calyx absent. Corolla (petals) absent. Stamens 2, 4-locular. Ovary superior; ovules 1–3.

Fruit: Utricles not winged; lying obliquely or straight in the pouch. Seeds ribbed.

Ploidy: 2n = 20; 40; 50; 60; 80

Habitat: naturalized; or possibly indigenous; occurring in ditches; ponds; taro paddies; and even on wet cliffs.

Elevation Range: