Cyperus virens |
Cyperus papyrus |
|
---|---|---|
green flatsedge |
Egyptian paper-reed, papyrus |
|
Habit | Herbs, perennial, cespitose; rhizomes 0.5–2 cm, often absent. | Herbs, perennial, rhizomatous, stout. |
Culms | trigonous, (20–)60–70(–100) cm × 2.4–6.9 mm, scabrid on angles. |
roundly trigonous, 300–500 cm × 15–45 mm, glabrous. |
Leaves | 4–12, flat to V-shaped, with readily visible cross ribs especially on abaxial surface, 20–50 cm × 3–14 mm. |
bladeless. |
Inflorescences | heads digitate to hemispheric, 1–3.5 cm diam.; rays 6–12, 1–9(–14) cm; 2d order rays often present, (0.5–)1–3 cm; 3d order rays occasionally present, 5–12 mm; bracts 4–8, horizontal to ascending at 30°, with prominent cross ribs,V-shaped, (1.5–)3–50(–75) cm × 0.5–13 mm; 2d order bracts 3–10 × 1–2 mm. |
spikes loosely cylindric, 10–20 × 6–10 mm; rays 40–100, drooping or arching, slender, 10–30 cm; 2d order rays 8–20 cm; bracts 4–10, ± erect, V-shaped, 3–8 cm × 4–15 mm; 2d order bracts 2–5, (1.5–)4–16 cm × 0.5–2 mm; rachilla persistent, separating laterally, remaining firmly attached basally, wings 0.3–0.4 mm wide. |
Spikelets | 10–40(–50), oblong to linear-lanceoloid, 5–18 × 2–3.2 mm; floral scales 10–40, pale grayish brown, or greenish, proximally greenish or brownish, oblanceolate, 2-keeled, weakly to distinctly 1-ribbed, proximal half 2-ribbed, (1.3–)1.5–2(–2.4) × 0.9–1.4 mm, apex acute (sometimes mucronulate), apically glabrous, occasionally scabridulous. |
6–30, slightly compressed, linear, ± quadrangular, 6–10 × 0.8–1 mm; floral scales 6–16, reddish beside 5-ribbed green medial part, white to hyaline near margins, ovate-elliptic, 1.8–2.2 × 1.2–1.5 mm, apex acute to obtuse. |
Flowers | stamens 1–2; anthers 0.8–1.4 mm; styles 0.8–1 mm; stigmas 0.6–0.8 mm. |
anthers 0.8–1 mm (connectives prolonged beyond anther as red subulate appendage 0.2–0.5 mm, apex usually setose); styles 0.2–0.4 mm; stigmas 0.8–1.2 mm. |
Achenes | brown, slightly to distinctly stipitate, ellipsoid (2.7–4.1 times as long as wide), (0.9–)1.2–1.5 × 0.3–0.4 mm, apical beak 0.1–0.5 mm, surfaces glabrous. |
pale brown, sessile, oblong, 0.8–1 × 0.4 mm, apex scarcely apiculate, surfaces puncticulate. |
Cyperus virens |
Cyperus papyrus |
|
Phenology | Fruiting spring–fall. | Fruiting summer. |
Habitat | Wet pastures, marshes, roadside ditches | Stream banks, marshes |
Elevation | 0–30 m (0–100 ft) | |
Distribution |
AL; FL; GA; LA; MS; NC; SC; TX; Mexico; Central America; South America
|
FL; s Europe; sw Asia; Africa [Introduced in North America] |
Discussion | Cyperus virens was found as waif in California in the 1800s (M. F. Denton 1978b; G. C. Tucker 1993b). Cyperus virens is readily distinguished from other species of subg. Pycnostachys by its trigonous culms, scabrid angles, and leaves and inflorescence bracts conspicuously septate by numerous cross ribs between the main ribs. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Cyperus papyrus is conspicuous in the field by its great height, leafless culm, and open, hemispheric inflorescence with drooping rays. Ancient Egyptians, Greeks, and Romans prepared paper from the pith of the culms of Cyperus papyrus, which is abundant along the Nile River. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 153. | FNA vol. 23, p. 173. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Name authority | Michaux: Fl. Bor.-Amer. 1: 28. (1803) | Linnaeus: Sp. Pl. 1: 47. (1753) |
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