Haspan Flatsedge

Description based on material from India and Africa. Kern (Fl. Malesiana 1974) claimed that correct spelling of epithet should be "halpan", which appears not to be true [Wilson, Cyperaceae Newsletter 9: 8. 1991; and Telopea 5: 598. 1994].

Herbs, perennial, cespitose, shortly rhizomatous. Culms trigonous, (2–)25–60(–100) cm × 1–4 mm, soft (flattened in drying), glabrous. Leaves usually reduced to sheaths, occasionally with blades, flat to V-shaped, (3–)10–30 cm × (1–)2.5–5 mm. Inflorescences: heads loosely digitate; rays (5–)10–12(–15), 1–15(–20) cm; 2d order rays usually present, (1–)6–12(–25) mm; 3d order rays sometimes present, 1–6 mm; bracts 2(–3), horizontal to ascending at 30–60°, longer (3–)6–18 cm × 2–4 mm, shorter (0.5–)2.5–6.5 cm × 1–2(–3) mm. Spikelets 1–15, linear-lanceoloid, ± compressed-quadrangular, 3–18 × 1–1.6 mm; floral scales 10–20(–40), laterally reddish to greenish brown, dull, often clear-edged, medially greenish, laterally 1-ribbed, medially 1-ribbed, oblong to obovate, 1–1.5(–1.9) × 0.8–1 mm, apex mucronate, glabrous except for cluster of crystalline prickles at apex. Flowers: stamens 3; anthers 0.3–0.5 mm; styles 0.4–0.9 mm; stigmas 0.5–0.8(–1.3) mm. Achenes white or reddish brown, stipitate, globose to obovoid or ellipsoid, 0.5–0.6(–0.7) × 0.3–0.4(–0.5) mm, base nearly cuneate, stipe 0.1 × 0.1–0.2 mm, apex obtuse to acute, apiculate or entire, surfaces granular to papillose.

Annual or perennial, 15-40 cm. Roots fibrous, reddish. Rhizome short, horizontal or ascending, with short internodes. Stem 1-2 mm diam., sharply trigonous, sides concave, smooth. Leaves c. half of stem length; sheaths up to 10 cm, usually distinctly reddish, soft, mouth oblique or, in leaves with blades, nearly straight; ligule 0; blades few, up to c. 15 cm, 2-3 mm wide, flat or channelled, margins and keel smooth, apex acute, slightly scabrous. Inflorescence a compound anthelodium, up to 90 mm; 1-2 bracts foliose, up to 70 mm, shorter than inflorescence; primary branches 7-12, up to 70 mm; secondary anthelodia 5-20 mm long, bracts glume-like; cluster of spikes 5-10 mm, formed by (1-)3-8 sessile spikes; spikes 3-12 x c. 1 mm, with 8-35 glumes; glume-like bract c. 1 mm, glume-like prophyll clasping, rounded, bi-nerved, sterile, c. 0.8; rachis c. 0.5 mm wide, tetrangular, reddish brown, internodes c. 1 mm, not clearly winged; glumes 1.3-1.6 mm, cymbiform, acute, slightly keeled near slightly recurved and barbed apex, sides brown or reddish-brown, obscurely bi-nerved, glossy, margins narrowly scarious. Stamens 3. Nut 1-1.4 x 0.8-1 mm, obovoid or ellipsoid, trigonous, white-reticulate or white-papillose.

Ala., Fla., Ga., La., Miss., N.C., S.C., Tex., Va.; Mexico; Central America; South America; Asia; Africa; Australia.

Distribution: In tropics of Old and New World; Africa S of Sahara, East Africa, Pakistan, India eastwards.

Fl. Per.: July - November.

Fruiting summer.

Swales between dunes, marshes, pond shores; 0–200m.

Rice fields (common acc. to Cooke, 1908 and Stewart, 1972).

Cyperus autumnalis Vahl; C. haspan subsp. juncoides (Lamarck) Kükenthal; C. haspan var. americanus Boeckeler; C. juncoides Lamarck