Cyperus laevigatus |
Cyperus haspan |
|
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smooth cyperus, smooth flatsedge, smooth nutgrass |
haspan flatsedge |
|
Habit | Herbs, perennial, rhizomatous. | Herbs, perennial, cespitose, shortly rhizomatous. |
Culms | single or close together, trigonous to ± terete, (1–)8–30(–60) cm × (0.3–)0.6–1.5(–2.2) mm, glabrous. |
trigonous, (2–)25–60(–100) cm × 1–4 mm, soft (flattened in drying), glabrous. |
Leaves | blades present or reduced to sheaths, base of culm covered with reddish sheath 5–25 mm, distally short toothed 1–2 mm, or leaf blades involute, 1–7 cm × 0.3–1(–1.6) mm. |
usually reduced to sheaths, occasionally with blades, flat to V-shaped, (3–)10–30 cm × (1–)2.5–5 mm. |
Inflorescences | heads appearing lateral, spikes ± digitate, 5–15 × 5–15 mm; rays absent, sometimes 1, to 2 mm; bracts (1–)2(–3), longer bracts erect, appearing as continuation of culm, shorter bract(s) horizontal or ascending, longer bracts (1–)2–8(–12) cm × 0.5–3 mm, shorter (0.3–)1–4.5 cm × 0.2–1 mm. |
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–)2–7(–14), whitish green to reddish, compressed-turgid, ellipsoid to oblong-lanceoloid, 4–7(–12) × (1.6–)2–3(–3.6) mm; floral scales (8–)12–22, off-white, whitish with red speckles, or with single red spot 0.5 mm wide, medially whitish, oblong-laterally ribless or weakly 2-ribbed, medially weakly 1–3-ribbed, obovate to orbiculate, 1.5–2 × (1.3–)1.6–2 mm. |
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 | anthers (0.5–)0.7–1 mm, connective apex reddish, 0.1–0.2 mm; styles 0.8–1.2 mm; stigmas 0.7–1 mm. |
stamens 3; anthers 0.3–0.5 mm; styles 0.4–0.9 mm; stigmas 0.5–0.8(–1.3) mm. |
Achenes | gray, glossy, oblong-ellipsoid to ovoid, (1.2–)1.3–1.5(–1.8) × (0.7–)0.8–1(–1.2) mm, base cuneate to stipelike, apex apiculate, surfaces finely reticulate to papillate. |
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. |
Cyperus laevigatus |
Cyperus haspan |
|
Phenology | Fruiting summer. | Fruiting summer. |
Habitat | Alkaline grasslands, hotsprings, ditches, brackish marshes | Swales between dunes, marshes, pond shores |
Elevation | 0–1000 m (0–3300 ft) | 0–200 m (0–700 ft) |
Distribution |
AZ; CA; NC; TX; Mexico; South America; West Indies; Europe; Asia; Africa
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AL; FL; GA; LA; MS; NC; SC; TX; VA; Mexico; Central America; South America; Asia; Africa; Australia
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Discussion | Cyperus laevigatus is one of only two species of subg. Juncellus in the New World. It can be distinguished from all other New World species of Cyperus by its two stigmas and disclike, strongly flattened achene, which is borne with its face toward the rachilla. Species of subg. Pycreus, especially C. niger, have been misidentified as C. laevigatus, probably because of the dark, shiny spikelets. All species of subg. Pycreus have biconvex achenes like C. laevigatus; in species of subg. Pycreus the achene is attached with an edge toward the rachilla; in C. laevigatus the achene faces the rachilla. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 23, p. 164. | FNA vol. 23, p. 151. |
Parent taxa | Cyperaceae > Cyperus > subg. Juncellus | Cyperaceae > Cyperus > subg. Pycnostachys |
Sibling taxa | ||
Synonyms | Acorellus laevigatus, Chlorocyperus laevigatus, Juncellus laevigatus, Pycreus laevigatus | C. autumnalis, C. haspan subsp. juncoides, C. haspan var. americanus, C. juncoides |
Name authority | Linnaeus: Mant. Pl. 2: 179. (1771) | Linnaeus: Sp. Pl. 1: 45. (1753) |
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