Cyperus involucratus
Cyperus entrerianus
umbrella flatsedge, umbrella-plant
woodrush flatsedge
trigonous, 30–150 cm × 1–5(–8) mm.
1–3, trigonous to roundly trigonous, (30–)40–65(–95) cm × (1–)2–3 mm.
bladeless.
(1–)5–10, V-shaped, (10–)30–45(–70) cm × 3–7 mm.
heads digitate, 15–30(–36) mm diam.;
rays (14–)20–22, (2–)5–12(–20) cm; 2d order rays 0.3–3(–4) cm; 3d order rays sometimes present, 0.3–2.5 cm;
bracts (4–)18–22, ± horizontal, flat, 15–27 cm × (1.5–)8–12 mm.
heads loosely to densely globose-ovoid, (6–)10–12(–20) mm diam.;
rays 6–10(–12), 1–8(–12) cm; 2d order rays 1–4, 5–15(–23) mm;
bracts (5–)6–8(–10), ascending at 45–60(–75)°, V-shaped, (5–)15–40(–55) cm × (1–)3–7 mm.
8–20, ovoid to linear-lanceoloid, compressed, 5–25 × 1.5–2 mm;
floral scales 8–28, laterally whitish or light brown, ± hyaline, medially light brown, laterally ribless, medially 3-ribbed, 2-keeled in proximal 30–60%, deltate-ovate, 1.6–2.4 × (1–)1.2–1.5(–1.7) mm, apex acute.
(1–)30–50(–65), greenish white, linear to broadly ellipsoid, flattened, 4–6.5 × 1.8–3.2 mm;
floral scales (10–)16–20(–26), laterally clear, pale green, off-white, or light brown, medially green or light brown, laterally weakly 1-ribbed, medially 2-ribbed, basally 2-keeled, oblong-lanceolate, (1.2–)1.4–1.6(–1.8) × (0.7–)0.8–1 mm, apex acute, mucronate, distally glabrous or scabridulous.
stamens 3;
anthers 0.7–1 mm;
styles 0.5–1 mm;
stigmas 0.6–1 mm.
stamen 1;
anthers ellipsoid, 0.6–0.7 mm, connective apex acute, 0.1–0.2 mm;
styles 0.2–0.4 mm;
stigmas 0.4–0.6 mm.
brown, sessile or stipitate, broadly ellipsoid, 0.6–0.8 × 0.4–0.6 mm, stipe if present to 0.1 mm, apex obtuse, apiculate, surfaces puncticulate.
brown, stipitate, ellipsoid to narrowly ellipsoid, broadly rounded or contracted basally, gradually tapered toward apex, 0.9–1.1 × 0.3–0.4 mm, stipe 0.1 mm, apex acute, surfaces finely reticulate.
Cyperus involucratus
Cyperus entrerianus
Cyperus involucratus has been collected in New York (R. S. Mitchell and G. C. Tucker 1997).
Cyperus involucratus is widely cultivated as a water plant in greenhouses and outdoors in warm-temperate or tropical climates. It has long been misidentified in the flora as C. alternifolius Linnaeus, an endemic of Madagascar (G. C. Tucker 1983).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Cyperus entrerianus is a recent introduction in the southern United States (earliest collection from Pensacola County, Florida, Brinker 413, MO in 1941). It has been confused with C. luzulae. The species that Boeckeler had first described 50 years earlier was accepted by G. Kükenthal (1935–1936). Cyperus entrerianus was accepted as a variety of C. luzulae by A. B. Ayers (1946); M. F. Denton (1978b) considered C. entrerianus a synonym of C. luzulae, stating that the features of these two taxa merged so completely throughout their geographic ranges that C. entrerianus could not be given specific status. Cyperus luzulae in the strict sense does not extend northward to North America.
Morphologic differences between Cyperus entrerianus and C. luzulae are as follows (G. C. Tucker 1994). Cyperus entrerianus has culms 40–75 cm; inflorescence bracts ascending at 45–60°; primary rays ascending at 45–60(–75)°; 2d order rays present; heads of spikelets loosely globose-ovoid, light greenish white to golden brown; rachilla dark red with stramineous scale scars; and scale apices acute. Cyperus luzulae has culms 20–40 cm; inflorescence bracts approximately horizontal; primary rays ascending at 15–30°; 2d order rays absent; heads of spikelets densely oblong to pyramidal, bright to dull white; rachilla green throughout; and scale apices rounded.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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