Description

Key Characters:

Growth Form: Plants coarse and stout, glabrous perennial herbs of wet or swampy habitats, with extensive starchy creeping rhizomes, often forming large dense colonies.

Stems: Stems erect, 1–3 m long, unbranched, terminating in an inflorescence.

Roots: Fibrous root system.

Leaves: Leaves simple. Alternate, distichous and erect. Blades linear, nearly all basal, blades flattened, usually spongy in texture, with longitudinal partitions connecting the upper and lower surfaces, and numerous cross partitions connecting the longitudinal ones; leaves 12–16 per vegetative stem, pale green, nearly flat, 8–20 mm wide. Base sheath open to base. Surfaces glaucous when fresh. Margins entire. Veins parallel. Sheaths open to base, the scarious upper margins tapering or rarely truncate. Stipules absent.

Flowers: Flowers numerous in dense, cylindrical, complex spikes, staminate spikes above pistillate ones, the spikes contiguous or separated, most of the flowers axillary to short bristle-like bracts. Flowers unisexual; Staminate and pistillate spikes contiguous or occasionally separated by an interval up to 2.5 cm long; staminate spikes pale brown, the flowers with simple hairs, stamens on branched filaments, pollen yellow or occasionally orange, in tetrads; pistillate spikes dark brown, 10–18 cm long, 1.5–3 cm in diameter, flowers without scales or hairs, on slender, often hair-like, compound pedicels 1–2 mm long. Calyx (sepals) absent. Corolla (petals) absent. Stamens 1–3 in staminate flowers, absent in pistillate flowers. Ovary superior, 1-carpellate, elevated on a gynophore that elongates in fruit to form a slender stipe; ovule 1, pendulous from near apex of carpel, apotropous or anatropous; style terminal, elongating and persistent in fruit; stigma linear to spatulate, dry.

Fruit: Fruit small; dry; tardily dehiscent; wind–dispersed; ellipsoid; (0.9–) 1.2–1.5(–1.6) mm long. Seeds with a slender; cylindrical embryo surrounded by copious mealy endosperm and thin perisperm.

Ploidy: 2n = 30

Habitat: Marshes.

Elevation Range: