Cyperus digitatus |
Cyperus fugax |
|
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finger flatsedge |
withering flatsedge |
|
Habit | Herbs, perennial, rhizomatous, coarse. | Herbs, annual, cespitose. |
Culms | trigonous, 50–150 cm × 2–15 mm, glabrous (rarely sparsely scabridulous on angles proximal to bracts). |
(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 | inversely W-shaped, 40–100 cm × 5–15 mm. |
V-shaped, (1–)3–5(–10) cm × (0.5–)1–2 mm. |
Inflorescences | spikes 1–4, cylindric, (2.5–)3.5–5 × 1.2–1.5 cm; rays 8–10, (1–)15–35 cm; 2d order rays 1–3 cm; bracts 8–12, ascending at 45–60°, (5–)20–80 cm × 3–15 mm; 2d order bracts 3–7 cm × 2–4 mm; rachilla persistent, wings 0.3 mm wide, at achene maturation adaxial edge of wing detaching from rachilla, base remaining firmly attached. |
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 | 35–65, slightly compressed, linear, ± quadrangular, 5–8 × 0.8–1.1 mm; floral scales deciduous, 12–16, appressed, marginally clear, laterally reddish along midrib, medially green, laterally 1–2-ribbed, medially strongly 5-ribbed, ovate, 1.6–1.8 × 1.1–1.3 mm, apex mucronulate. |
(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 | anthers 0.4–0.5 mm, connective blunt, at most 0.1 mm; styles 0.8–1 mm; stigmas 0.4 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 or whitish, sessile, ellipsoid, slightly wider at base, 0.9 × 0.4 mm, surfaces finely 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 digitatus |
Cyperus fugax |
|
Phenology | Fruiting summer. | Fruiting early summer. |
Habitat | Wet pastures, stream banks | Wet, disturbed sandy soils in full sun |
Elevation | 0–100 m (0–300 ft) | 0–200 m (0–700 ft) |
Distribution |
FL; TX; Mexico; Central America; South America; Asia; Africa |
LA; TX; Central America; West Indies (Cuba); South America (Ecuador) |
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.) |
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Source | FNA vol. 23, p. 173. | FNA vol. 23, p. 159. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | C. inconspicuus, C. tenellus | |
Name authority | Roxburgh: Fl. Ind. 1: 209. (1820) | Liebmann: Kongel. Danske Vidensk. Selsk. Skr., Naturvidensk. Math. Afd., ser. 5, 2: 196. (1850) |
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