Cyperus virens |
Cyperus involucratus |
|
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green flatsedge |
umbrella flatsedge, umbrella-plant |
|
Habit | Herbs, perennial, cespitose; rhizomes 0.5–2 cm, often absent. | Herbs, perennial, cespitose, rhizomatous. |
Culms | trigonous, (20–)60–70(–100) cm × 2.4–6.9 mm, scabrid on angles. |
trigonous, 30–150 cm × 1–5(–8) mm. |
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. |
heads digitate, 15–30(–36) mm diam.; rays (14–)20–22, (2–)5–12(–20) cm; 2d order rays 0.3–3(–4) cm; 3d order rays sometimes present, 0.3–2.5 cm; bracts (4–)18–22, ± horizontal, flat, 15–27 cm × (1.5–)8–12 mm. |
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. |
8–20, ovoid to linear-lanceoloid, compressed, 5–25 × 1.5–2 mm; floral scales 8–28, laterally whitish or light brown, ± hyaline, medially light brown, laterally ribless, medially 3-ribbed, 2-keeled in proximal 30–60%, deltate-ovate, 1.6–2.4 × (1–)1.2–1.5(–1.7) mm, apex acute. |
Flowers | stamens 1–2; anthers 0.8–1.4 mm; styles 0.8–1 mm; stigmas 0.6–0.8 mm. |
stamens 3; anthers 0.7–1 mm; styles 0.5–1 mm; stigmas 0.6–1 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. |
brown, sessile or stipitate, broadly ellipsoid, 0.6–0.8 × 0.4–0.6 mm, stipe if present to 0.1 mm, apex obtuse, apiculate, surfaces puncticulate. |
Cyperus virens |
Cyperus involucratus |
|
Phenology | Fruiting spring–fall. | Fruiting early summer–fall. |
Habitat | Wet pastures, marshes, roadside ditches | Damp, disturbed soils, ditches, stream banks |
Elevation | 0–100(–800) m (0–300(–2600) ft) | |
Distribution |
AL; FL; GA; LA; MS; NC; SC; TX; Mexico; Central America; South America
|
CA; FL; LA; TX; e 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 involucratus has been collected in New York (R. S. Mitchell and G. C. Tucker 1997). Cyperus involucratus is widely cultivated as a water plant in greenhouses and outdoors in warm-temperate or tropical climates. It has long been misidentified in the flora as C. alternifolius Linnaeus, an endemic of Madagascar (G. C. Tucker 1983). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 153. | FNA vol. 23, p. 150. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Pycnostachys |
Sibling taxa | ||
Name authority | Michaux: Fl. Bor.-Amer. 1: 28. (1803) | Rottbøll: Descr. Pl. Rar., 22. (1772) |
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