Description

Key Characters:

Growth Form: Annuals, or sometimes apparently short-lived perennials under favorable conditions.

Stems:

Roots:

Leaves: Leaves simple. alternate Blades flat, linear, usually shorter than the culm, 6–18 mm wide. Margins entire. Stipules absent.

Flowers: Flowers in inflorescences large, open, decompound, umbelliform, 10–40 cm long, 15–60 cm wide, primary rays 10–12, spreading, 6–30 cm long, usually 2–branched, the secondary rays 3–8, 2–8 cm long, tertiary rays 0–2 cm long, spikes somewhat loosely disposed, oblong-cylindrical, 2–4 cm long, 1.5–3 cm wide; involucral bracts 6–8, the lower ones 2–3 times as long as the inflorescence, up to 17 mm wide, secondary involucral bracts as long as or slightly longer than the secondary umbelliform corymb; spikelets 20–50 per tertiary ray, 10–25–flowered, spreading to reflexed, linear, subterete, 10– 25 mm long. 1–1.5 mm wide, rachilla flexuous, winged, the wings obovate, with a slightly recurved apex, ca. 1 mm long, ca. 0.7 mm wide, eventually becoming thickened and corky, tightly clasping the achene; glumes yellowish brown with darker reddish brown striations, ovate–oblong, laxly imbricate, 2–3.5 mm long, 1.2–1.5 mm wide, weakly convolute, margins hyaline, apex subacute, 7–9–nerved, midnerve green, prolonged into a terminal mucro.

Fruit: Achenes oblong–oblanceoloid to oblong–ellipsoid; trigonous; 1.5–2 mm long; ca. 0.5 mm wide.

Ploidy:

Habitat: Apparently rare in low elevation wet sites; such as margins of ponds and vernal pools; taro paddies; and along streams.

Elevation Range: