Description

Key Characters:

Growth Form: Glabrous, aquatic perennial herbs of fresh water, with creeping slender rhizomes.

Stems: Stems erect, leafy.

Roots: Fibrous root system.

Leaves: Leaves simple. Alternate, occasionally the upper ones subopposite. Blades of submerged leaves filiform or flattened and grass-like, the upper leaves floating and blades expanded, with a well–developed open sheath at the base. Surfaces glabrous. Petiolate or sheathing, Sometimes with a ligule at the apex which is a projection of the petiole, occasionally petioles attached further down the sheath or directly to the node and the sheath appearing to form a large adaxial or intrapetiolar sheathing stipule.

Flowers: Flowers in axillary and terminal, bractless, often somewhat fleshy spikes elevated above the water. Flowers small, wind–pollinated, bisexual (perfect), actinomorphic. Perianth of 4 distinct, fleshy, clawed tepals in 1 series. Stamens 4 in 1 series, opposite the tepals, adnate to the claw; anthers subsessile, dithecal, opening by longitudinal slits, extrorse. Pollen spheric. Ovary superior, carpels 4, distinct, alternate with the stamens; ovule 1, attached to the ventral margin of the carpel usually toward the base, orthotropous, usually becoming campylotropous or anatropous after fertilization; style short, terminal, or absent; stigma dry, not papillose.

Fruit: Fruit of distinct achenes or drupelets; usually buoyant in water; the pericarp partly aerenchymatous. Seeds without endosperm.

Ploidy:

Habitat: Aquatic.

Elevation Range: