Description

Key Characters:

Growth Form: Aquatic or semiaquatic, scapose annual or perennial herbs.

Stems: Rhizomatous.

Roots: Fibrous root system.

Leaves: Leaves simple. Alternate, crowded into a basal rosette, submerged or emersed. Primary veins parallel from base of blade to apex, secondary veins reticulate. Petiolate. Stipules absent.

Flowers: Flowers, in verticillate, racemose inflorescences; inflorescence branches whorled. Flowers unisexual (and the plants monoecious or occasionally dioecious), lower ones usually pistillate, upper ones staminate, or with some bisexual (perfect). Calyx of 3 sepals, usually reflexed, persistent, ± withering. Corolla of 3 petals, white, deciduous. Stamens numerous; anthers 2-loculed, dehiscing longitudinally. 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 flattened; ribbed or winged and with a short; erect or divergent beak. Seeds without endosperm; embryo U-shaped.

Ploidy:

Habitat: Aquatic or semiaquatic.

Elevation Range: