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southern flatsedge

shining flatsedge, slender flatsedge

Habit Herbs, perennial, rhizomatous. Herbs, annual, densely cespitose, with fibrous roots.
Culms

trigonous, (15–) 20–40(–65) cm × 0.5–1 mm, glabrous.

roundly trigonous, 3–25(–30) cm × 0.3–1.4 mm, glabrous.

Leaves

V-shaped, (10–)20–40 cm × 0.8–2.8(–3) mm, glabrous.

1–3, V-shaped, 1–8 cm × 1–2 mm.

Inflorescences

spike 1, densely oblong-cylindric, (15–)25–35(–40) × 12–18(–22) mm, (spikelets loosely spaced, 7–9 per 5 mm of rachis);

rays (5–)6–8(–11), 0.5–4(–7.5) cm;

bracts (4–)5–7(–8), ascending at 30º, (4–)10–30(–35) cm × (1–)2–4(–7) mm;

rachilla deciduous, wings persistent, 0.4–0.5 mm wide.

spike 1, loosely ovoid, compressed, 7–14 × 9–14 mm;

rays 1–4, to 2(–3) cm;

bracts 2–3, horizontal to ascending at 30(–45)°, V-shaped to flat, 1–12 cm × 0.5–1.5 mm.

Spikelets

(20–)40–80(–100), linear, ± cylindric, scarcely compressed, (4.5–)6–9(–11) × (0.5–) 0.6–0.7(–1) mm;

floral scales persistent, (1–)2–3(–4), appressed, medially green, laterally light brown to tawny or bronze, medially (1–)3-ribbed, laterally 3-ribbed, oblong, (2.6–)2.8–3.2(–3.4) × (1–)1.2(–1.4) mm, apex acute, mucronulate, mucro to 0.1(–0.2) mm.

3–5(–8), flattened, oblong to oblong-lanceoloid, 8–18 × 2–2.6(–3) mm;

floral scales (6–)10–26(–32), closely imbricate, laterally light to dark brown, medially light brown, laterally ribless, medially 2–3-ribbed, 2-keeled, oblong to ovate, 1.9–2.7 × 1.8–2.3 mm, apex obtuse.

Flowers

anthers 0.6–0.8 mm;

styles (0.4–)0.6–1(–1.2) mm;

stigmas persistent on achenes, prominently exserted from floral scales, (1.5–)2–3(–4) mm.

stamens 2–3;

anthers 0.4–0.5 mm, connective not prolonged;

styles 0.6–1 mm;

stigmas 1–1.5 mm.

Achenes

brown to reddish brown, stipitate, narrowly oblong, 1.8–2.1 × (0.4–)0.5(–0.7) mm, stipe 0.1–0.2 × 0.1–0.2 mm, apex apiculate, acute, surfaces puncticulate.

black, network of ridges forming isodiametric or square cells, sessile, obovoid to ovoid, 1–1.3(–1.5) × (0.6–)0.8 mm, apex apiculate, surfaces minutely punctate.

Cyperus thyrsiflorus

Cyperus bipartitus

Phenology Fruiting summer. Fruiting summer.
Habitat Dry, open woods Emergent shorelines, ditches, puddles, often in disturbed places
Elevation 0–200 m (0–700 ft) 0–1500 m (0–4900 ft)
Distribution
from FNA
AL; FL; GA; LA; TX; Mexico; South America; West Indies
[BONAP county map]
from FNA
AL; AR; AZ; CA; CO; CT; DC; DE; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; ON; QC; Mexico; Central America; South America
[WildflowerSearch map]
[BONAP county map]
Source FNA vol. 23, p. 185. FNA vol. 23, p. 161.
Parent taxa Cyperaceae > Cyperus > subg. Cyperus 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. 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. virens
C. acuminatus, C. aggregatus, C. alopecuroides, C. amabilis, C. articulatus, 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. virens
Synonyms C. anceps, C. dissitiflorus, C. pallens, C. regiomontanus var. pallens, C. tribrachiatus, Mariscus dissitiflorus, Mariscus pallens, Mariscus tribrachiatus C. rivularis
Name authority Junghuhn: Linnaea 6: 24. (1831) Torrey: Ann. Lyceum Nat. Hist. New York 3: 257. (1836)
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