Description

Key Characters:

Growth Form: Fronds free-floating on water surface, 2–5 cohering in groups connected by elongate, peltately attached stipes.

Stems: The paired "leaves" are actually modified stems.

Roots: Roots (4)5–12, fascicled.

Leaves: Leaves absent. Blades obovate to orbicular, (3–)4–8(–10) mm long, 2–6 mm wide, reproducing primarily by asexual budding, over–wintering buds dark brown and reniform, arising from the reproductive pouches and growing nearly to maturity before separating from the parent plant. Upper surfaces dark green; lower surfaces reddish. 5–11(–15) conspicuous radiating veins that create a peltate appearance,. Stipules absent.

Flowers: Flowers in saclike spathes open only at apex, with 2 staminate flowers consisting of a solitary anther and 1 pistillate flower consisting of a single ovary with 1–2 ovules. Flowers usually 3 in each pouch, 2(3) staminate and 1 pistillate in 1–2 lateral pouches on either side of the basal end of the frond, enclosed in a spathe. Flowers unisexual. Calyx (sepals) absent. Corolla (petals) absent. Stamens 2, 4-locular. Ovary superior; ovules 1–2 .

Fruit: Fruit slightly winged. Seeds compressed; smooth or slightly reticulate.

Ploidy: 2n = 30; 40

Habitat: naturalized; or possibly indigenous; occurring in taro paddies; slow–running streams; ponds; and marshes; documented only from O'ahu; but probably more widespread.

Elevation Range: