Description

Key Characters:

Growth Form: Perennial herbs, to 150 cm; rhizomes absent; stolons present; corms present.

Stems:

Roots: Fibrous root system.

Leaves: Leaves simple. Submersed and emersed. Submersed leaves sessile, phyllodial, flattened, to 26 × 0.5 cm; emersed leaves with petiole ± triangular, 21–70.5 cm, blade linear–ovate to ovate, 4.6–16.4 × 0.7–6.1 cm. Margins entire. Petioles ± triangular, 21–70.5 cm. Stipules absent.

Flowers: Flowers in inflorescences in racemes, of 3–9 whorls, emersed, 2.5–10 × 2–4.5 cm; peduncles 22–60 cm; bracts connate more than ¼ total length, lanceolate, 3–5.5 mm, delicate, not papillose; fruiting pedicels spreading to recurved, cylindric, 0.5–3 cm. Flowers unisexual, to 1.8 cm diameter. Calyx of 3 sepals, spreading to recurved, not enclosing flower or fruiting head. Corolla of 3 petals, white, deciduous. Stamens numerous; filaments dilated, longer than anthers, pubescent; pistillate pedicellate, without ring of sterile stamens. Ovary superior, carpels numerous, spirally arranged in a crowded head on a large globose receptacle; ovules 1-2, restricted to base of pistil, anatropous or amphitropous; style terminal or basilateral; stigma often decurrent.

Fruit: Achenes oblanceoloid; not abaxially keeled; 1.2–2 × 0.8–1.2 mm; beaked; faces tuberculate; wings absent; glands absent; beak lateral; horizontal to erect; 0.3–0.6 mm. Fruiting heads 0.7–1.2 cm diam. Seeds without endosperm; embryo U-shaped.

Ploidy: 2n = 22

Habitat: Streams and lakes.

Elevation Range: 0–900 m.