Cyperus retrofractus |
Cyperus alopecuroides |
|
---|---|---|
rough flatsedge |
foxtail flatsedge |
|
Habit | Herbs, perennial, cespitose. | Herbs, perennial, rhizomatous, coarse. |
Culms | with cormlike bases, sharply trigonous, 25–90 cm, glabrous proximally, minutely scabridulous distally. |
trigonous, 150–250 cm × 2–15 mm, glabrous. |
Leaves | V-shaped, 14–40 cm × 3.5–8 mm, (pubescent on adaxial side of midrib). |
inversely W-shaped, 30–150 cm × 6–22 mm. |
Inflorescences | spikes loose, obtrulloid to obdeltoid (broadest near apex, nearly as long as wide), 20–28(–34) × (12–)15–30 mm; rays 4–13, (1–)4–24 cm (longest ray shorter than bracts), glabrous; bracts 3–12, ascending at 30–45°, flat, 3–25 cm × 3–7 mm; rachilla persistent, wings 0.4–0.6 mm wide, covering 3/4 of mature achene. |
spikes 1–4, cylindric, 1.5–4 cm × 7–15 mm; rays 3–9, 10–26 cm; 2d order rays 2–11 cm; 3d order rays 1–4 cm (or absent); bracts 3–5, ± horizontal, 20–100 cm × 3–15 mm; 2d order bracts 2–7 cm × 2–7 mm; 3d order bracts 2–5 cm × 2–4 mm (or absent); rachilla persistent, wingless or wing hyaline, narrow, 0.1 mm wide. |
Spikelets | 30–50, proximal one reflexed, distal ones divaricate, linear-lanceoloid, ± terete, (6.5–) 8–10(–17) × 0.5–0.7 mm; floral scales persistent, 3–6(–8), appressed, stramineous (suffused with reddish purple), 4–5-ribbed laterally, ovate-lanceolate, (4–)4.4–4.9(–5.4) × 1.3–1.5 mm; terminal scale not spinose, apex straight, excurved mucronate, or cuspidate. |
50–100, linear, ± quadrangular, slightly compressed, 8–11 × 0.9–1.2 mm; floral scales 15–30, marginally clear, laterally reddish along midrib, medially green, laterally 3–4 ribbed, medially 3–5-ribbed, ovate, 1–2–1.6 × 1.1–1.3 mm, apex mucronulate. |
Flowers | anthers 0.7–1.2 mm; styles 1.5–2 mm; stigmas 2–2.5 mm. |
anthers 2, 0.4–0.5 mm; styles 0.8–1 mm; stigmas 2, 0.4 mm. |
Achenes | brown to brownish black, narrowly oblong, (2.2–)2.5–3 × 0.6–0.7 mm, base cuneate, apex obtuse, apiculate, surfaces puncticulate. |
dark brown, sessile, ellipsoid to obovoid, 0.9 × 0.4–0.5 mm, surfaces finely puncticulate. |
Cyperus retrofractus |
Cyperus alopecuroides |
|
Phenology | Fruiting summer. | Fruiting summer. |
Habitat | Roadsides, pastures, disturbed sites in sandy or clayey soils | Pond shores, stream banks |
Elevation | 0–300 m (0–1000 ft) | 0–30 m (0–100 ft) |
Distribution |
AL; AR; DC; DE; GA; KY; MO; NC; NJ; OH; PA; SC; TN; VA
|
FL; West Indies; Asia; Africa; Australia [Introduced in North America] |
Discussion | For information concerning nomenclature of Cyperus retrofractus, see J. R. Carter and C. E. Jarvis (1986). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Cyperus alopecuroides has been introduced in Polk County, Florida. Plants of Cyperus alopecuroides might be confused with C. digitatus; large size and the biconvex achenes with two stigmas characterize C. alopecuroides. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 180. | FNA vol. 23, p. 173. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Scirpus retrofractus, C. dipsaciformis, C. retrofractus var. dipsaciformis, Mariscus retrofractus | |
Name authority | (Linnaeus) Torrey: in J. Carey, Carices North. U.S., 519. (1847) | Rottbøll: Descr. Pl. Rar., 20. (1772) |
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