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umbrella-plant

withering flatsedge

Habit Herbs, perennial, cespitose, rhizomatous. Herbs, annual, cespitose.
Culms

trigonous, 30–150 cm × 1–5(–8) mm.

(1–)10–30(–60) together, roundly trigonous proximally, trigonous distally, (0.5–)3–6(–12) cm × (0.2–)0.4–0.8 mm, glabrous.

Leaves

bladeless.

V-shaped, (1–)3–5(–10) cm × (0.5–)1–2 mm.

Inflorescences

heads digitate, 15–30(–36) mm diam.;

rays (14–)20–22, (2–)5–12(–20) cm; 2d order rays 0.3–3(–4) cm; 3d order rays sometimes present, 0.3–2.5 cm;

bracts (4–)18–22, ± horizontal, flat, 15–27 cm × (1.5–)8–12 mm.

spikes loosely ovoid, 8–15(–25) mm wide;

rachis 1–3 mm;

rays (1–)2–4(–6), (0.5–)1–3(–6) cm; 2d order rays absent;

bracts (1–)2–4(–5), ascending at 30–45°, V-shaped, (1–)2.5–6(–11) cm × 0.5–1.8 mm.

Spikelets

8–20, ovoid to linear-lanceoloid, compressed, 5–25 × 1.5–2 mm;

floral scales 8–28, laterally whitish or light brown, ± hyaline, medially light brown, laterally ribless, medially 3-ribbed, 2-keeled in proximal 30–60%, deltate-ovate, 1.6–2.4 × (1–)1.2–1.5(–1.7) mm, apex acute.

(2–)4–6(–10), linear-lanceoloid, strongly flattened, (5–)8–12(–18) × 1.2–1.5 (1.8) mm;

floral scales (5–)10–16(–32), laterally clear, stramineous or light reddish brown, medially green, laterally ribless, medially 3(–5)-ribbed, ovate, (1.2–)1.3–1.6(–2) × 1–1.2(–1.4) mm, apex obtuse, mucronate to minutely mucronulate.

Flowers

stamens 3;

anthers 0.7–1 mm;

styles 0.5–1 mm;

stigmas 0.6–1 mm.

stamens 2;

anthers 0.1–0.2 mm;

styles 0.1–0.3(–0.4) mm;

stigmas 0.3–0.4 mm.

Achenes

brown, sessile or stipitate, broadly ellipsoid, 0.6–0.8 × 0.4–0.6 mm, stipe if present to 0.1 mm, apex obtuse, apiculate, surfaces puncticulate.

light to dark brown, glossy or iridescent, stipitate, oblong-obovoid, 0.9–1.1 × 0.4–0.5 mm, stipe 0.1 mm, apex truncate, apiculate, surfaces punctate.

Cyperus involucratus

Cyperus fugax

Phenology Fruiting early summer–fall. Fruiting early summer.
Habitat Damp, disturbed soils, ditches, stream banks Wet, disturbed sandy soils in full sun
Elevation 0–100(–800) m [0–300(–2600) ft] 0–200 m [0–700 ft]
Distribution
from FNA
CA; FL; LA; TX; e Africa [Introduced in North America]
[BONAP county map]
from FNA
LA; TX; Central America; West Indies (Cuba); South America (Ecuador)
[BONAP county map]
Discussion

Cyperus involucratus has been collected in New York (R. S. Mitchell and G. C. Tucker 1997).

Cyperus involucratus is widely cultivated as a water plant in greenhouses and outdoors in warm-temperate or tropical climates. It has long been misidentified in the flora as C. alternifolius Linnaeus, an endemic of Madagascar (G. C. Tucker 1983).

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

Cyperus fugax is known from Louisiana from an early nineteeth century collection from “western Louisiana” (Hale s.n., TCD).

Cyperus fugax has been treated as a form of C. polystachyos (G. Kükenthal 1935–1936; A. B. Ayers 1946); nevertheless, specific status is appropriate. The most conspicuous differences are the annual habit and small size (less than 12 cm) of C. fugax; C. polystachyos is a perennial of moderate size (mostly taller than 20 cm). Other differences are summarized below.

Cyperus polystachyos is characterized as a shortly rhizomatous perennial; floral scales oblong, 1.8–2.4 mm, closely imbricate; styles 0.6–1 mm; stigmas 1.4–2 mm; anthers 0.6–0.8 mm; achenes substipitate to cuneate, slightly compressed laterally.

Cyperus fugax is characterized as a nonrhizomatous annual; floral scales ovate, 1.3–1.6 mm, loosely imbricate; styles 0.1–0.2 mm; stigmas 0.3–0.4 mm; filaments 1.2–1.4 mm; anthers 0.1–0.2 mm; achenes stipitate, strongly compressed laterally.

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

Source FNA vol. 23, p. 150. Treatment authors: Gordon C. Tucker*, Brian G. Marcks*, J. Richard Carter *. FNA vol. 23, p. 159. Treatment authors: Gordon C. Tucker*, Brian G. Marcks*, J. Richard Carter *.
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. 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. 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. inconspicuus, C. tenellus
Name authority Rottbøll: Descr. Pl. Rar., 22. (1772) Liebmann: Kongel. Danske Vidensk. Selsk. Skr., Naturvidensk. Math. Afd., ser. 5, 2: 196. (1850)
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