FNA: Cyperus fugax

	Cyperus fugax
	withering flatsedge
Habit	Herbs, annual, cespitose.
Culms	(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	V-shaped, (1–)3–5(–10) cm × (0.5–)1–2 mm.
Inflorescences	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	(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 2; anthers 0.1–0.2 mm; styles 0.1–0.3(–0.4) mm; stigmas 0.3–0.4 mm.
Achenes	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 fugax
Phenology	Fruiting early summer.
Habitat	Wet, disturbed sandy soils in full sun
Elevation	0–200 m (0–700 ft)
Distribution	LA; TX; Central America; West Indies (Cuba); South America (Ecuador) [BONAP county map]
Discussion	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. 159.
Parent taxa	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. 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	Liebmann: Kongel. Danske Vidensk. Selsk. Skr., Naturvidensk. Math. Afd., ser. 5, 2: 196. (1850)
Web links	Local Web sites: LA Plants WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Cyperus fugax

withering flatsedge

Habit

Herbs, annual, cespitose.

Culms

(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

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

Inflorescences

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

(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 2;

anthers 0.1–0.2 mm;

styles 0.1–0.3(–0.4) mm;

stigmas 0.3–0.4 mm.

Achenes

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 fugax

Phenology

Fruiting early summer.

Habitat

Wet, disturbed sandy soils in full sun

Elevation

0–200 m (0–700 ft)

Distribution

LA; TX; Central America; West Indies (Cuba); South America (Ecuador)

[BONAP county map]

Discussion

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. 159.

Parent taxa

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. 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

Liebmann: Kongel. Danske Vidensk. Selsk. Skr., Naturvidensk. Math. Afd., ser. 5, 2: 196. (1850)

Web links

Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).

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Cyperus fugax

Cyperus fugax