Finger Flat Sedge

Herbs, perennial, rhizomatous, coarse. Culms trigonous, 50–150 cm × 2–15 mm, glabrous (rarely sparsely scabridulous on angles proximal to bracts). Leaves inversely W-shaped, 40–100 cm × 5–15 mm. Inflorescences: spikes 1–4, cylindric, (2.5–)3.5–5 × 1.2–1.5 cm; rays 8–10, (1–)15–35 cm; 2d order rays 1–3 cm; bracts 8–12, ascending at 45–60°, (5–)20–80 cm × 3–15 mm; 2d order bracts 3–7 cm × 2–4 mm; rachilla persistent, wings 0.3 mm wide, at achene maturation adaxial edge of wing detaching from rachilla, base remaining firmly attached. Spikelets 35–65, slightly compressed, linear, ± quadrangular, 5–8 × 0.8–1.1 mm; floral scales deciduous, 12–16, appressed, marginally clear, laterally reddish along midrib, medially green, laterally 1–2-ribbed, medially strongly 5-ribbed, ovate, 1.6–1.8 × 1.1–1.3 mm, apex mucronulate. Flowers: anthers 0.4–0.5 mm, connective blunt, at most 0.1 mm; styles 0.8–1 mm; stigmas 0.4 mm. Achenes brown or whitish, sessile, ellipsoid, slightly wider at base, 0.9 × 0.4 mm, surfaces finely puncticulate.

Perennial, 60-150 cm. Rhizome short, horizontal, covered by brown or dark-brown scales. Stem 2-8 mm diam., trigonous, edges obtuse below, smooth, sides in upper part often concave. Leaves basal, shorter than stem; sheaths up to 20 cm, yellowish or brown, soft, one side scarious, mouth margin concave; blades 50 cm or longer, 6-12 mm wide, flat or folded, keeled, margins narrowly revolute, smooth or distally scabrous, apex long-attenuate, trigonous, scabrous. Inflorescence a compound anthelodium, 10-25 cm; bracts, 6-9 lowermost leaf-like, longest more than 50 cm; primary branches mostly 6-9, to 15 cm, with tubular prophyll up to 20 mm; secondary anthelodia 4-10 cm; cluster of spikes 30-50 mm long, with 30-60 spikes; spikes spirally arranged, reflexed, 7-13 x c. 2 mm, glume-like bract 1.5-2 mm, acute, glume-like prophyll 1.6-2 mm, binerved; rachis rigid, flat, reddish brown, internodes c. 1 mm; glumes 2.5-2.8 mm, acute, midnerve area green, sides with 2-3 conspicuous veins and often with reddish-brown zone, margins widely scarious, basal edges extending down to next node. Nut 1.3-1.5 x 0.4-0.5 mm, ovoid, trigonous, grey-brown, very finely reticulate.

Tropical and subtropical regions of both hemispheres.

Fla., Tex.; Mexico; Central America; South America; Asia; Africa.

Distribution: Pantropical; in SE Asia from Pakistan, India and Sri Lanka to S. China, Philippines, Malaysia and SE Australia.

1100 m

Fl. Per.: July-August.

Fruiting summer.

Wet pastures, stream banks; 0–100m.

Open wet places, swamps, rice fields.