Cyperus compressus L. (1753)

Distribution: Pantropical, except Australia; extending from India to Afghanistan; in Himalayas up to 1200 m.

600-1200 m

Annual, 3-27 cm, forming small tufts. Stem 0.5-2 mm diam., sharply trigonous, smooth. Leaves from half to slightly shorter than stem; sheaths up to 50 mm, lowest blade-less, greenish grey, yellowish or often slightly brownish, soft, mouth margin wide, slightly concave; blades up to 16 cm, 2.5 mm wide, flat or folded, keeled, margins slightly revolute, smooth, apex acute, scabrous. Inflorescence a simple anthelodium, to 10 cm, or single cluster of spikes, primary branches 0-4, up to 85 mm, tubular prophyll up to 8 mm; lowest 3-5 bracts foliose, 3-20 cm; cluster of spikes 10-20 cm, with 3-9 digitately arranged spikes; spikes 8-20 x c. 4 mm, compressed, ovoid or elongate ellipsoid, green to yellowish brown, glume-like bract c. 2.7 mm, acute, glume-like prophyll c. 1.7 mm, blunt; rachis compressed, c. 0.7 mm wide, narrowly winged, grey, brown-dotted, internodes 0.5-1 mm; glumes c. 4 mm, arista 0.5-0.7 mm, sides with several prominent nerves, grey, brown-dotted, margins scarious. Stamens 2-3; stigmas 3. Nut 1.5-1.7 x c. 1.2 mm, obovoid, plano-convex, rather sharply trigonous, yellowish brown, smooth.

Herbs, annual, cespitose with fibrous roots. Culms trigonous, (2–)6–15(–35) cm × (0.3–)1–1.8 mm, glabrous. Leaves 1–5, flat to V-shaped, (1–)5–15(–22) cm × (0.5–)1.5–3 mm. Inflorescences: spikes ± digitate, ± globose, 7–40 × 10–20 mm; rays (0–)1–6, 2–12 cm; if absent, inflorescence a sessile cluster of (1–)3–10 spikelets; rachis 2–5 mm; bracts (1–)4–5(–6), ascending, V-shaped, 1–15(–20) cm × 0.5–3.5 mm; rachilla persistent, wingless. Spikelets (1–)3–12(–16), greenish white, linear to linear-lanceoloid, compressed-quadrangular, 6–34(–40) × 2–3(–3.6) mm; floral scales deciduous, (8–)16–36(–42), spreading, laterally whitish, greenish, or pale brownish, medially green, weakly 7–9-ribbed, laterally weakly 1–2-ribbed, most ribs medial, ovate, (2.4–)2.6–3 × (1.9–)2–2.4(–2.5) mm, apex acute to ± acute, cuspidate tip (0.3–)0.5–0.7(–0.8) mm. Flowers: anthers 0.6–0.7 mm; styles 0.9–1.3 mm; stigmas 0.5–0.8 mm. Achenes brown, stipitate to sessile, obovoid, (1–)1.2–1.4(–1.5) × 0.9–1(–1.1) mm, apex obtuse to emarginate, surfaces very finely puncticulate.