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woodrush flatsedge

Rusby's flatsedge, Rusby's sedge

Habit Herbs, perennial, coarse; rhizomes (seldom collected) indurate, oblique, 5–12 mm wide, with fibrous brown floral scales, 1–5 cm. Herbs, perennial, rhizomatous.
Culms

1–3, trigonous to roundly trigonous, (30–)40–65(–95) cm × (1–)2–3 mm.

basally cormlike, trigonous, (8–)15–40(–60) cm × (0.4–)0.8–1.5(–2) mm, glabrous or sparsely to densely scabridulous to minutely scabrid on angles or usually on surface, just proximal to bracts or over distal few centimeters.

Leaves

(1–)5–10, V-shaped, (10–)30–45(–70) cm × 3–7 mm.

(1–)3–4, V-shaped, (7–)15–25(–40) cm × 1–3(–5) mm, sparsely minutely scabridulous on margins and keel in distal 1/3, otherwise glabrous.

Inflorescences

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.

spikes 1–3, sessile (occasionally 1 spike on peduncle 5–20 cm, produced from axil of distalmost leaf), loosely cylindric to oblong-ovoid, (9–)15–30(–45) × (3–)8–15(–18) mm;

bracts 2–3(–7), longest erect, or very nearly so, others spreading, (1–)3–20(–26) cm × (0.5–)1–3(–5) mm;

rays (1–)2–6(–11), (1–)2–7(–12) cm, in some depauperate plants rays less than 1 cm;

rachilla ± deciduous, wingless.

Spikelets

(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.

(4–)8–25(–35), oblong-ellipsoid to linear, compressed-quadrangular, (2–)7–11(–15) × (2–)2.4–3.2(–3.5) mm;

floral scales (1–)4–8(–14), laterally dull whitish, stramineous, or light brown, or reddish brown to deep red, often red-dotted especially near keel, medially greenish, broadly ovate-deltate to ± orbiculate, laterally strongly 3(–4)-ribbed, medially weakly 1–3-ribbed, (1.6–)1.8–2.4 × (1.8–)2.2–2.8 mm, margins clear, erose especially apically, apex obtuse, tipped with straight mucro 0.1–0.2(–0.3) mm.

Flowers

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.

anthers 0.4–0.6 mm;

styles 0.4(–0.8) mm;

stigmas 0.6–1 mm.

Achenes

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.

finely reticulate with isodiametric cells, this layer gradually wearing away to reveal inner brown to reddish brown layer, stipitate, ovoid to obovoid, 1.4–1.6(–1.9) × 1–1.3(–1.4) mm, base cuneate to ± attenuate, stipe 0.1–0.2 × 0.2 mm, apex obtuse, slightly apiculate, inner layer papillose.

Cyperus entrerianus

Cyperus sphaerolepis

Phenology Fruiting summer. Fruiting summer.
Habitat Roadside ditches, marshes Clearings in montane forests
Elevation 0–100 m (0–300 ft) 1000–2500 m (3300–8200 ft)
Distribution
from FNA
AL; FL; GA; LA; MS; TX; Mexico; South America; Central America (Nicaragua) [Introduced in North America]
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; NM; TX; Mexico
[BONAP county map]
Discussion

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.)

Cyperus sphaerolepis has long been known by the synonym C. rusbyi and has been treated as a variety of C. fendlerianus. Specific status for C. sphaerolepis is supported by B. G. Marcks (1972) and G. C. Tucker (1994).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 23. FNA vol. 23, p. 177.
Parent taxa Cyperaceae > Cyperus > subg. Pycnostachys Cyperaceae > Cyperus > subg. Cyperus
Sibling taxa
C. acuminatus, C. aggregatus, C. alopecuroides, C. amabilis, C. articulatus, C. bipartitus, C. cephalanthus, C. compressus, C. croceus, C. cuspidatus, C. dentatus, C. dentoniae, C. diandrus, C. difformis, C. digitatus, C. dipsaceus, C. distans, C. distinctus, C. drummondii, C. echinatus, C. elegans, C. eragrostis, C. erythrorhizos, C. esculentus, C. fendlerianus, C. filicinus, C. filiculmis, C. filiformis, C. flavescens, C. flavicomus, C. floribundus, C. fugax, C. fuligineus, C. fuscus, C. giganteus, C. gracilis, C. granitophilus, C. grayi, C. grayoides, C. haspan, C. hermaphroditus, C. houghtonii, C. hypopitys, C. hystricinus, C. involucratus, C. iria, C. laevigatus, C. lancastriensis, C. lanceolatus, C. lecontei, C. lentiginosus, C. ligularis, C. lupulinus, C. manimae, C. microiria, C. mutisii, C. niger, C. ochraceus, C. odoratus, C. onerosus, C. ovatus, C. owanii, C. oxylepis, C. pallidicolor, C. papyrus, C. parishii, C. pilosus, C. planifolius, C. plukenetii, C. polystachyos, C. prolifer, C. prolixus, C. pseudothyrsiflorus, C. pseudovegetus, C. pumilus, C. reflexus, C. refractus, C. retroflexus, C. retrofractus, C. retrorsus, C. rotundus, C. sanguinolentus, C. schweinitzii, C. serotinus, C. seslerioides, C. setigerus, C. spectabilis, C. sphacelatus, C. sphaerolepis, C. squarrosus, C. strigosus, C. surinamensis, C. tetragonus, C. thyrsiflorus, C. virens
C. acuminatus, C. aggregatus, C. alopecuroides, C. amabilis, C. articulatus, C. bipartitus, C. cephalanthus, C. compressus, C. croceus, C. cuspidatus, C. dentatus, C. dentoniae, C. diandrus, C. difformis, C. digitatus, C. dipsaceus, C. distans, C. distinctus, C. drummondii, C. echinatus, C. elegans, C. entrerianus, C. eragrostis, C. erythrorhizos, C. esculentus, C. fendlerianus, C. filicinus, C. filiculmis, C. filiformis, C. flavescens, C. flavicomus, C. floribundus, C. fugax, C. fuligineus, C. fuscus, C. giganteus, C. gracilis, C. granitophilus, C. grayi, C. grayoides, C. haspan, C. hermaphroditus, C. houghtonii, C. hypopitys, C. hystricinus, C. involucratus, C. iria, C. laevigatus, C. lancastriensis, C. lanceolatus, C. lecontei, C. lentiginosus, C. ligularis, C. lupulinus, C. manimae, C. microiria, C. mutisii, C. niger, C. ochraceus, C. odoratus, C. onerosus, C. ovatus, C. owanii, C. oxylepis, C. pallidicolor, C. papyrus, C. parishii, C. pilosus, C. planifolius, C. plukenetii, C. polystachyos, C. prolifer, C. prolixus, C. pseudothyrsiflorus, C. pseudovegetus, C. pumilus, C. reflexus, C. refractus, C. retroflexus, C. retrofractus, C. retrorsus, C. rotundus, C. sanguinolentus, C. schweinitzii, C. serotinus, C. seslerioides, C. setigerus, C. spectabilis, C. sphacelatus, C. squarrosus, C. strigosus, C. surinamensis, C. tetragonus, C. thyrsiflorus, C. virens
Synonyms C. luzulae var. entrerianus C. fendlerianus var. debilis, C. fendlerianus var. leucolepis, C. leucolepis, C. rusbyi, C. schweinitzii var. debilis
Name authority Boeckeler: Flora 61: 139. (1878) Boeckeler: Linnaea 35: 609. (1868)
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