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green flatsedge

plains flatsedge

Habit Herbs, perennial, cespitose; rhizomes 0.5–2 cm, often absent. Herbs, perennial, cespitose, rhizomatous; base cormlike; rhizomes scaly, 12 cm × 2 mm.
Culms

trigonous, (20–)60–70(–100) cm × 2.4–6.9 mm, scabrid on angles.

trigonous, 20–55 cm × 1.2–11.8 mm, glabrous.

Leaves

4–12, flat to V-shaped, with readily visible cross ribs especially on abaxial surface, 20–50 cm × 3–14 mm.

V-shaped, 12–30 cm × 2–3 mm.

Inflorescences

heads digitate to hemispheric, 1–3.5 cm diam.;

rays 6–12, 1–9(–14) cm; 2d order rays often present, (0.5–)1–3 cm; 3d order rays occasionally present, 5–12 mm;

bracts 4–8, horizontal to ascending at 30°, with prominent cross ribs,V-shaped, (1.5–)3–50(–75) cm × 0.5–13 mm; 2d order bracts 3–10 × 1–2 mm.

heads digitate, 12–20 mm diam.;

rays 7–12, 1–13 cm; 2d order rays 1–3 cm (sometimes absent);

bracts 3–5, longest ± erect, V-shaped, 5–12(–18) cm × 2–3 mm.

Spikelets

10–40(–50), oblong to linear-lanceoloid, 5–18 × 2–3.2 mm;

floral scales 10–40, pale grayish brown, or greenish, proximally greenish or brownish, oblanceolate, 2-keeled, weakly to distinctly 1-ribbed, proximal half 2-ribbed, (1.3–)1.5–2(–2.4) × 0.9–1.4 mm, apex acute (sometimes mucronulate), apically glabrous, occasionally scabridulous.

(8–)20–30, linear-lanceoloid, compressed, 5–10(–14) × 1.4–1.7 mm;

floral scales (8–)16–26, laterally brown to reddish brown, medially green, laterally 1-ribbed, medially 3-ribbed, broadly elliptic, 2–2.5 × 1.2–1.6 mm, apex with slightly excurved cusp 0.2–0.3 mm.

Flowers

stamens 1–2;

anthers 0.8–1.4 mm;

styles 0.8–1 mm;

stigmas 0.6–0.8 mm.

stamens 3;

anthers 1 mm, connective apex reddish, subulate, 0.1 mm;

styles 1–1.5 mm;

stigmas 1.5 mm.

Achenes

brown, slightly to distinctly stipitate, ellipsoid (2.7–4.1 times as long as wide), (0.9–)1.2–1.5 × 0.3–0.4 mm, apical beak 0.1–0.5 mm, surfaces glabrous.

white to light brown, sessile, ellipsoid, 0.7–0.8 × 0.25–0.35 mm, apex obtuse, apiculate, surfaces puncticulate.

Cyperus virens

Cyperus onerosus

Phenology Fruiting spring–fall. Fruiting early summer (May–Jun).
Habitat Wet pastures, marshes, roadside ditches Permanent pools and wet swales between sand dunes
Elevation 1200 m (3900 ft)
Distribution
from FNA
AL; FL; GA; LA; MS; NC; SC; TX; Mexico; Central America; South America
[WildflowerSearch map]
[BONAP county map]
from FNA
TX
[BONAP county map]
Discussion

Cyperus virens was found as waif in California in the 1800s (M. F. Denton 1978b; G. C. Tucker 1993b).

Cyperus virens is readily distinguished from other species of subg. Pycnostachys by its trigonous culms, scabrid angles, and leaves and inflorescence bracts conspicuously septate by numerous cross ribs between the main ribs.

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

Of conservation concern.

Cyperus onerosus is apparently restricted to Andrews and Winkler counties in Texas.

This interesting endemic is most similar to Cyperus dentatus; it lacks tubers and apparently is not proliferous.

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

Source FNA vol. 23, p. 153. FNA vol. 23, p. 151.
Parent taxa Cyperaceae > Cyperus > subg. Pycnostachys Cyperaceae > Cyperus > subg. Pycnostachys
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. 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. sphaerolepis, C. squarrosus, C. strigosus, C. surinamensis, C. tetragonus, C. thyrsiflorus
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. 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
Name authority Michaux: Fl. Bor.-Amer. 1: 28. (1803) M. C. Johnston: SouthW. Naturalist 9: 308. (1964)
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