Cyperus laevigatus |
Cyperus distinctus |
|
---|---|---|
smooth cyperus, smooth flatsedge, smooth nutgrass |
swamp flatsedge |
|
Habit | Herbs, perennial, rhizomatous. | Herbs, perennial, cespitose, rhizomatous. |
Culms | single or close together, trigonous to ± terete, (1–)8–30(–60) cm × (0.3–)0.6–1.5(–2.2) mm, glabrous. |
terete, 40–60(–90)cm, 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. |
flat, 35–70 cm × 4–9(–12) 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 hemispheric, 10–20 mm diam.; rays 5–9(–14), 3.5–10 cm; 2d order rays 0.5–2 cm; bracts 5–10, ± horizontal, flat, 12–40(–50) cm × 2–7 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. |
(25–)35–50(–60), ovoid, compressed, (3.5–)5–12(–14) × 2.5–3.5(–4) mm; floral scales 10–32, golden brown to brown, 2-keeled, laterally ribless, narrowly lanceolate, 2–2.2(–3) × 0.8–1.4 mm. |
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. |
stamen 1; anthers 1 mm; styles 1 mm; stigmas 0.5 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. |
brown, stipitate, narrowly ellipsoid, 1.5–2 × 0.2–0.4 mm, base swollen, spongy, stipe 0.2 × 0.2–0.3 mm, apex acute, beak slender, 0.2 mm, surfaces puncticulate. |
Cyperus laevigatus |
Cyperus distinctus |
|
Phenology | Fruiting summer. | Fruiting summer. |
Habitat | Alkaline grasslands, hotsprings, ditches, brackish marshes | Damp grasslands, roadsides, ditches |
Elevation | 0–1000 m (0–3300 ft) | 0–50 m (0–200 ft) |
Distribution |
AZ; CA; NC; TX; Mexico; South America; West Indies; Europe; Asia; Africa
|
FL; GA; LA; SC; West Indies (Bahamas) |
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.) |
The slender achenes with conspicuously swollen bases distinguish Cyperus distinctus from other species of subg. Pycnostachys. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 164. | FNA vol. 23, p. 154. |
Parent taxa | Cyperaceae > Cyperus > subg. Juncellus | Cyperaceae > Cyperus > subg. Pycnostachys |
Sibling taxa | ||
Synonyms | Acorellus laevigatus, Chlorocyperus laevigatus, Juncellus laevigatus, Pycreus laevigatus | C. virens var. brittonii |
Name authority | Linnaeus: Mant. Pl. 2: 179. (1771) | Steudel: Syn. Pl. Glumac. 2: 24. (1855) |
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