Cyperus difformis |
Cyperus sphaerolepis |
|
---|---|---|
Asian flatsedge, smallflower umbrella sedge, variable flatsedge |
Rusby's flatsedge, Rusby's sedge |
|
Habit | Herbs, annual, cespitose. | Herbs, perennial, rhizomatous. |
Culms | 1–15, trigonous, 7–30 cm × 1.2–2.5 mm, soft (flattened in pressing), glabrous. |
basally cormlike, trigonous, (8–)15–40(–60) cm × (0.4–)0.8–1.5(–2) mm, glabrous or sparsely to densely scabridulous to minutely scabrid on angles or usually on surface, just proximal to bracts or over distal few centimeters. |
Leaves | 2–7, flat, (2–)7–22 cm × 2.2–4 mm. |
(1–)3–4, V-shaped, (7–)15–25(–40) cm × 1–3(–5) mm, sparsely minutely scabridulous on margins and keel in distal 1/3, otherwise glabrous. |
Inflorescences | heads dense, 7–17 mm diam.; when rays short, heads sessile or nearly so, then densely irregularly lobate, 12–35 mm diam.; rays 1–5, 2–32 mm; bracts 2–4, longest bract erect or nearly so, appearing as continuation of culm, other bracts horizontal to ascending, 1–22 cm × 0.5–3.5 mm, margins and keel minutely scabridulous. |
spikes 1–3, sessile (occasionally 1 spike on peduncle 5–20 cm, produced from axil of distalmost leaf), loosely cylindric to oblong-ovoid, (9–)15–30(–45) × (3–)8–15(–18) mm; bracts 2–3(–7), longest erect, or very nearly so, others spreading, (1–)3–20(–26) cm × (0.5–)1–3(–5) mm; rays (1–)2–6(–11), (1–)2–7(–12) cm, in some depauperate plants rays less than 1 cm; rachilla ± deciduous, wingless. |
Spikelets | 30–120, greenish brown to purplish brown, oblong-ellipsoid, compressed, (2–)3–5(–6) × 0.8–1.2 mm; floral scales (6–)12–20(–30), laterally clear margins, stramineous to deep purple, medially greenish, stramineous, or purplish, laterally ribless, medially 3-ribbed, obovate to orbiculate, 0.6–0.8 × 0.6–0.8 mm, apex mucronulate. |
(4–)8–25(–35), oblong-ellipsoid to linear, compressed-quadrangular, (2–)7–11(–15) × (2–)2.4–3.2(–3.5) mm; floral scales (1–)4–8(–14), laterally dull whitish, stramineous, or light brown, or reddish brown to deep red, often red-dotted especially near keel, medially greenish, broadly ovate-deltate to ± orbiculate, laterally strongly 3(–4)-ribbed, medially weakly 1–3-ribbed, (1.6–)1.8–2.4 × (1.8–)2.2–2.8 mm, margins clear, erose especially apically, apex obtuse, tipped with straight mucro 0.1–0.2(–0.3) mm. |
Flowers | stamens 1 or 2; anthers ovoid-ellipsoid, 0.1 mm, connective not prolonged; styles 0.1 mm; stigmas 0.1–0.3 mm. |
anthers 0.4–0.6 mm; styles 0.4(–0.8) mm; stigmas 0.6–1 mm. |
Achenes | light brown, obovoid-ellipsoid, 0.6–0.8 × 0.3–0.4 mm (as long as subtending scale), base cuneate, apex obtuse, apiculate, surfaces finely reticulate, papillose. |
finely reticulate with isodiametric cells, this layer gradually wearing away to reveal inner brown to reddish brown layer, stipitate, ovoid to obovoid, 1.4–1.6(–1.9) × 1–1.3(–1.4) mm, base cuneate to ± attenuate, stipe 0.1–0.2 × 0.2 mm, apex obtuse, slightly apiculate, inner layer papillose. |
Cyperus difformis |
Cyperus sphaerolepis |
|
Phenology | Fruiting summer. | Fruiting summer. |
Habitat | Disturbed, muddy soils, shallow waters | Clearings in montane forests |
Elevation | 0–1000 m (0–3300 ft) | 1000–2500 m (3300–8200 ft) |
Distribution |
AL; AZ; CA; FL; GA; ID; KY; LA; MS; NC; NJ; NM; OR; PA; SC; TN; TX; VA; Mexico; South America; West Indies (Puerto Rico); Central America (Nicaragua, Panama); Eurasia; Indian Ocean Islands; Pacific Islands; Australia [Introduced in North America]
|
AZ; NM; TX; Mexico |
Discussion | Cyperus difformis is naturalized in the New World and native to the Old World, where it ranges from southern Europe to southern Africa and eastward to Southeast Asia and Australia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Cyperus sphaerolepis has long been known by the synonym C. rusbyi and has been treated as a variety of C. fendlerianus. Specific status for C. sphaerolepis is supported by B. G. Marcks (1972) and G. C. Tucker (1994). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 156. | FNA vol. 23, p. 177. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | C. lateriflorus | C. fendlerianus var. debilis, C. fendlerianus var. leucolepis, C. leucolepis, C. rusbyi, C. schweinitzii var. debilis |
Name authority | Linnaeus: Cent. Pl. II, 6. (1756) | Boeckeler: Linnaea 35: 609. (1868) |
Web links |