Cyperus floribundus |
Cyperus erythrorhizos |
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Rio Grande sedge |
red-root cyperus, red-root flat sedge, redroot nutgrass |
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Habit | Herbs, perennial, cespitose, rhizomatous. | Herbs, annual, cespitose. |
Culms | trigonous, basally tuberous thickened, 15–40 cm × 1–2.5 mm, glabrous. |
trigonous to roundly trigonous, (0.5–)5–25(–105) cm × 1–2.5(–7.5) mm, glabrous. |
Leaves | flat to V-shaped, 10–30 cm × 1–2 mm. |
flat to inversely W-shaped, 5–25(–90) cm × 2–5(–11) mm. |
Inflorescences | spike 1, densely oblong to ellipsoid, 8–36 × 8–20 mm; rays 4–12, 10–20 cm; bracts 3–6, horizontal to ascending at 30°, V-shaped, 3–15 cm × (3–)4–5.8 mm; rachilla deciduous, wings 0.5–0.7 mm wide. |
spikes 1–3(–6), rather densely cylindric-ovoid, (4–)10–30(–45) × (6–)10–16(–23) mm; rays 2–6(–12), 1–8(–28) cm; bracts (3–)5–7(–11), horizontal to ascending at 30°, inversely W-shaped, (3–)10–20(–70) cm × 1–3(–12) mm; rachilla persistent, at maturity becoming laterally free, remaining firmly attached proximally, wings 0.3(–0.4) mm wide. |
Spikelets | (5–)20–35(–60), linear to oblong, quadrangular; 4–12(–21) × 0.7–1.2 mm, base narrowed to 0.4–1 mm; floral scales persistent, 1–3(–5), appressed, laterally whitish to reddish brown, stramineous with reddish spots, medially green, laterally 3–6-ribbed (midrib distinctly scabrid at 30X), narrowly oblong to ovate, 2.6–4.8 × 1.6–2 mm; apex rounded to ± acute, entire, with mucro 0.3–0.5 mm; sterile terminal scale involute, 0.4–0.6 mm wide, uncinate; distal floral scales with cusp 0.6–1.9. |
(20–)40–80, linear, quadrangular, 3–8(–11) × 1–1.5 mm; floral scales deciduous, 6–16(–30), appressed, laterally light brown with reddish speckles, medially greenish, laterally ribless, medially 3-ribbed, oblong-ovate to obovate, quadrangular to subterete, 1.3–1.5 × 0.8–1.2 mm, apex obtuse, mucronulate. |
Flowers | anthers 0.5–1.3 mm; styles 0.4–0.5 mm; stigmas 0.5–0.9 mm. |
anthers 0.2–0.3 mm, connectives 0.1 mm; styles 0.7–0.8 mm; stigmas 0.4 mm. |
Achenes | light brown to reddish brown, sessile to slightly stipitate, narrowly ellipsoid, 1.8–2.4 × 0.6–0.8 mm, apex slightly apiculate, surfaces puncticulate. |
light grayish to brown, sessile, ovoid, (0.4–)0.7–1 × 0.4–0.6 mm, apex rounded, apiculate, surfaces glabrous. |
Cyperus floribundus |
Cyperus erythrorhizos |
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Phenology | Fruiting mid summer–early fall (Jul–Sep). | Fruiting summer. |
Habitat | Damp, disturbed soils, croplands | Emergent shorelines |
Elevation | 0–1000 m (0–3300 ft) | 0–1500 m (0–4900 ft) |
Distribution |
TX; Mexico |
AL; AR; AZ; CA; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; WA; WI; WV; MB; ON; Mexico (Baja California)
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Discussion | Included previously in Cyperus retroflexus (or its synonym C. uniflorus), C. floribundus has a much narrower geographic range (southern Texas and northeastern Mexico) and differs in features of spikelet morphology (J. R. Carter and S. D. Jones 1997). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 23. | FNA vol. 23, p. 172. |
Parent taxa | Cyperaceae > Cyperus > subg. Cyperus | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | C. uniflorus var. floribundus, C. uniflorus | C. cupreus, C. erythrorhizos var. cupreus, C. occidentalis, C. washingtonensis |
Name authority | (Kükenthal) J. Rich. Carter & S. D. Jones: Rhodora 99: 330. (1998) | Muhlenberg: Descr. Gram., 20. (1817) |
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