Cyperus retroflexus

Buckley

Proc. Acad. Nat. Sci. Philadelphia. 14: 9. 1862

Synonyms: Cyperus uniflorus var. floribundus Kükenthal Cyperus uniflorus var. retroflexus (Buckley) Kükenthal Mariscus uniflorus
Treatment appears in FNA Volume 23. Mentioned on page 186.

Herbs, perennial, cespitose, rhizomatous. Culms trigonous, basally tuberous-thickened, (5–)15–40(–80) cm × 1–2.5 mm, glabrous. Leaves flat to V-shaped, (5–)10–30(–60) cm × (0.5–)1–3(–4) mm. Inflorescences: spike 1, loosely to densely ovoid to cylindric, 8–36 × 8–20 mm; rays 3–6(–9), (5–)10–32 cm; bracts 3–6, horizontal to ascending at 30°, V-shaped, (1–)3–15(–30) cm × 0.5–4.5 mm; rachilla deciduous, wings 0.5–0.7 mm wide. Spikelets (5–)20–35(–65), linear to oblong (without narrowed basal portion), quadrangular; (2.2–)4–10(–18) × 0.7–1.1 mm; floral scales persistent, 1–5, appressed, pale greenish white laterally, stramineous with reddish dots, or deep red, greenish or light brown medially, 3–6-ribbed laterally, narrowly ovate to oblong-elliptic, 2.6–3.9 × 1.6–2 mm, apex rounded to ± acute, entire, mucronulate; distal scale with glabrous midrib and mucro 0.1–0.3(–0.5) mm; sterile terminal scale of spikelet only 0.4–0.6 mm wide, involute, frequently uncinate. Flowers: anthers (0.3–)0.4–0.6 mm; styles 0.4–0.5 mm; stigmas 0.5–0.9 mm. Achenes light brown to reddish brown, sessile or slightly stipitate, ellipsoid, (1.8–)2–2.4 × 0.6–0.8(–0.9) mm, apex slightly apiculate, surfaces puncticulate.


Phenology: Fruiting mid summer–early fall (Jul–Sep).
Habitat: Damp, disturbed soils, croplands
Elevation: 0–1000 m

Distribution

V23 321-distribution-map.jpg

Ala., Ariz., Ark., Miss., Mo., N.Mex., Okla., Tex., Mexico.

Discussion

Cyperus retroflexus is distinguished from other species of Cyperus with deciduous spikelets by the involute, sterile terminal scale of the spikelet. In plants with cuspidate scales, the terminal scale is usually somewhat recurved, giving the appearance of a hook at the end of the spikelet.

Selected References

None.

Lower Taxa

None.

... more about "Cyperus retroflexus"
Gordon C. Tucker* +, Brian G. Marcks* +  and J. Richard Carter * +
Buckley +
Ala. +, Ariz. +, Ark. +, Miss. +, Mo. +, N.Mex. +, Okla. +, Tex. +  and Mexico. +
0–1000 m +
Damp, disturbed soils, croplands +
Fruiting mid summer–early fall (Jul–Sep). +
Proc. Acad. Nat. Sci. Philadelphia. +
Cyperus uniflorus var. floribundus +, Cyperus uniflorus var. retroflexus +  and Mariscus uniflorus +
Cyperus retroflexus +
Cyperus subg. Cyperus +
species +