Cyperus schweinitzii |
Cyperus floribundus |
|
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sand flatsedge, Schweinitz's flatsedge |
Rio Grande sedge |
|
Habit | Herbs, perennial, rhizomatous. | Herbs, perennial, cespitose, rhizomatous. |
Culms | trigonous, (10–)20–50 cm × (0.6–)1–2 mm, glabrous or more often scabridulous, either in distal 1/2 or over entire length; basal sheaths, 1–3, light brown, 1–4 cm, papery. |
trigonous, basally tuberous thickened, 15–40 cm × 1–2.5 mm, glabrous. |
Leaves | flat to V-shaped, (2–)20–35 cm × 2–6 mm, margins and keel minutely scabridulous; proximal leaves bladeless. |
flat to V-shaped, 10–30 cm × 1–2 mm. |
Inflorescences | spikes ± umbellate to slenderly (infrequently broadly) ovoid, 10–25 × 7–16 mm; rays 3–5, 1.5–8(–15) cm; bracts 3–7, erect (or declined at most 25–30° from vertical), (2.5–)8–20(–25) cm × (0.5–)1.5–6 mm; rachilla ± deciduous, wingless. |
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. |
Spikelets | (1–)5–10(–20), oblong to linear-oblong, quadrangular, 7–10(–18) × (2.8–)3.2–4(–4.5) mm; floral scales deciduous, (1–)5–10(–14), spreading, laterally stramineous or dull whitish, sometimes also red-spotted, medially green, laterally 2–3-ribbed, medially 3-ribbed, broadly ovate to oblong-ovate, (2.3–)2.8–3.2 × (2–)2.4–3.2 mm, apex broadly rounded, often clear-erose, cusp 0.1–0.4 mm in proximal scales, 0.3–1 mm in distal scales. |
(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. |
Flowers | anthers 0.8–1.4 mm; styles 0.1–0.3 mm; stigmas 1.5–3 mm. |
anthers 0.5–1.3 mm; styles 0.4–0.5 mm; stigmas 0.5–0.9 mm. |
Achenes | light to dark brown or nearly black, broadly ellipsoid, infrequently obovoid, 2–2.4 × 0.9–1.4 mm, base cuneate to ± stipelike, apex obtuse to broadly rounded, surfaces papillose. |
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. |
2n | = 166. |
|
Cyperus schweinitzii |
Cyperus floribundus |
|
Phenology | Fruiting late spring–early summer. | Fruiting mid summer–early fall (Jul–Sep). |
Habitat | Riverbanks, sand bars, lakeshores, sand dunes, sandy openings in woods | Damp, disturbed soils, croplands |
Elevation | 0–1000 m (0–3300 ft) | 0–1000 m (0–3300 ft) |
Distribution |
CO; IA; IL; KY; MA; MI; MN; MO; MT; NJ; NM; NY; OH; OK; PA; SD; TX; UT; WA; WI; WY; AB; MB; ON; QC; SK; Mexico (Coahuila)
|
TX; Mexico |
Discussion | Cyperus schweinitzii is introduced, but not naturalized, in Massachusetts and Washington. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 23, p. 174. | FNA vol. 23. |
Parent taxa | Cyperaceae > Cyperus > subg. Cyperus | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | C. alterniflorus | C. uniflorus var. floribundus, C. uniflorus |
Name authority | Torrey: Ann. Lyceum Nat. Hist. New York 3: 276. (1836) | (Kükenthal) J. Rich. Carter & S. D. Jones: Rhodora 99: 330. (1998) |
Web links |