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bentawn flatsedge

umbrella flat sedge

Habit Herbs, perennial, cespitose; rhizomes elongate, scaly, 2–3 mm wide. Herbs, annual, cespitose, with fibrous roots.
Culms

roundly trigonous to terete, 30–80 cm × 1–1.6 mm, glabrous.

trigonous, 4–25(–35) cm, glabrous.

Leaves

1–6, 10–40 cm, glabrous or essentially so.

flat, 5–20 cm × 1.5–3 mm.

Inflorescences

heads ovoid to pyramidal, 9–15 mm diam.;

rays 0 or 3–6, 0.5–4 cm, glabrous;

bracts 3–4, longest erect, appearing as continuation of culm, others horizontal to ascending, 4–17 cm × 1.5–4 mm.

heads ± digitate, 12–22 mm diam.;

rays 3–6, 1–6 cm;

bracts 1–4, ± horizontal, flat, 1.5–15 cm × 1.5–3 mm.

Spikelets

25–60, reddish with contrasting yellowish or greenish edges, oblong-lanceoloid, strongly compressed, 5–6(–15) × 1.5–2.5 mm;

floral scales 10–22, laterally reddish, medially yellowish green, 2-keeled, laterally strongly 1-ribbed on each side, proximally grooved, ovate-elliptic, 1.4–2.2 × 0.8–1.5 mm, apex acute, apically scabridulous (sometimes glabrous).

6–12, oblong-lanceoloid, compressed, 5–10 × 2.8–3.2 mm;

floral scales 8–28, closely imbricate, stramineous to light brown or clear (marginal band bright red, spikelet thus appearing dark margined), laterally ribless, oblong to ovate, 2.5–3 × 1.6–1.9 mm.

Flowers

stamen 1;

anthers 0.6–1 mm;

styles 0.3–0.5 mm;

stigmas 0.3–0.6 mm.

stamens 2(–3);

anthers 0.3 mm, connective apex reddish, subulate, 0.1–0.2 mm;

styles 0.3–0.5 mm;

stigmas 2.2–3.1 mm.

Achenes

reddish brown, stipitate, ovoid-ellipsoid, 0.8–0.9 × 0.3–0.4 mm, stipe 0.1–0.2 mm, apex acute to acuminate, surfaces reticulate or subtly rugulose.

brown, network of ridges forming isodiametric or square cells, sessile or stipitate, obovoid to ovoid, 1–1.2 × 0.5–0.6 mm, stipe, if present, 0.1 mm, apex obtuse, apiculate, surfaces minutely punctate.

Cyperus reflexus

Cyperus diandrus

Phenology Fruiting late spring–fall (May–Oct). Fruiting summer.
Habitat Muddy soils or shallow waters Emergent shorelines, in sandy, peaty, or slightly brackish areas (though seldom where disturbed)
Elevation 0–200 m (0–700 ft) 0–600 m (0–2000 ft)
Distribution
from FNA
FL; LA; OK; TX; Mexico; Central America (Costa Rica)
[BONAP county map]
from FNA
CT; DE; IA; IL; IN; MA; MD; ME; MI; MN; MO; NE; NH; NJ; NY; PA; RI; VA; VT; NB; NS; ON; QC
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[BONAP county map]
Discussion

Cyperus reflexus is recognized by its reddish scales with contrasting greenish or yellow keels and by the laterally 1ribbed scales. The lateral rib is most often situated where the reddish and yellowish parts of the scale meet. Two varieties of C. reflexus, var. reflexus and var. fraternus, have been recognized (M. F. Denton 1978b). Both varieties were noted as intermingled in the North American and South American segments of the widely disjunct range of C. reflexus. Such variation does not seem significant at the varietal level (see G. C. Tucker 1994; G. C. Tucker and R. McVaugh 1993).

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

Source FNA vol. 23. FNA vol. 23, p. 161.
Parent taxa Cyperaceae > Cyperus > subg. Pycnostachys Cyperaceae > Cyperus > subg. Pycreus
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. 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. 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. virens
Synonyms C. arenicola, C. fraternus, C. pseudovegetus var. arenicola, C. reflexus var. fraternus Pycreus diander
Name authority Vahl: Enum. Pl. 2: 299. (1805) Torrey: Cat. Pl. New York, 90. (1819)
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