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Texas flatsedge

umbrella flat sedge

Habit Herbs, perennial, cespitose; rhizomes knotty, much branched, 2–5 mm diam., scaly. Herbs, annual, cespitose, with fibrous roots.
Culms

roundly trigonous, basally with dark fibrous remnants of old leaf sheaths, (0.5–)4–30 cm × 0.4 –1.1 mm, glabrous.

trigonous, 4–25(–35) cm, glabrous.

Leaves

1–5, flat, involute toward apex, 3–18 cm × 1–2.5(–3) mm.

flat, 5–20 cm × 1.5–3 mm.

Inflorescences

heads hemispheric to spheric, (3–)6–15(–24) mm diam.;

rays absent;

bracts 2–5, horizontal to reflexed, parallel to culm, 1–13 cm × 1–3 mm, margins and keel sparsely minutely scabridulous distally.

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

(5–)20–60(–100), whitish to greenish or brownish, ovoid to oblong-lanceoloid, compressed, 3–7 × 2–4 mm;

floral scales (8–)10–12(–24), laterally milky white (infrequently yellowish, pale greenish, brown, or bronze-white), medially green or white, laterally ribless, medially 3-ribbed, ovate to ovate-lanceolate, 1.6–3(–3.4) × 0.8–1.3 mm, apex mucronate to acuminate.

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

stamens 3;

anthers linear, (0.4–)0.6–0.8(–1.1) mm, connective not prolonged;

styles 0.8–1.8 mm;

stigmas (0.5–)1–1.5(–2) 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

brown to blackish, trigonous, broadly obovoid, 0.5–1 × 0.3–0.75 mm, base slightly stipelike, ± cuneate to rounded, apex apiculate, papillose.

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 seslerioides

Cyperus diandrus

Phenology Fruiting summer. Fruiting summer.
Habitat Seeps, damp meadows in montane forests Emergent shorelines, in sandy, peaty, or slightly brackish areas (though seldom where disturbed)
Elevation 1000–2000 m (3300–6600 ft) 0–600 m (0–2000 ft)
Distribution
from FNA
AZ; TX; Mexico; South America; Central America (Honduras)
[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
[WildflowerSearch map]
[BONAP county map]
Source FNA vol. 23, p. 157. 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. reflexus, C. refractus, C. retroflexus, C. retrofractus, C. retrorsus, C. rotundus, C. sanguinolentus, C. schweinitzii, C. serotinus, 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 Pycreus diander
Name authority Kunth: in A. von Humboldt et al., Nov. Gen. Sp. 1: 209. (1816) Torrey: Cat. Pl. New York, 90. (1819)
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