Cyperus flavescens |
Cyperus plukenetii |
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pale flatsedge, yellow flatsedge |
Plukenet's flatsedge, Plukenet's sedge |
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Habit | Herbs, annual, cespitose. | Herbs, perennial, cespitose. |
Culms | trigonous, (2–)4–30 cm × 0.4–2 mm, glabrous. |
basally cormlike, obtusely trigonous to subterete, 25–100 cm × 2–4 mm, densely minutely scabridulous. |
Leaves | 1–5, (blades often absent, base of culm with 1 reddish sheath bearing minute blade tooth 1–2 mm), (3–)10–18 cm × (0.5–)1.5–2(–2.6) mm. |
inversely W-shaped, 20–70 cm × 4–7 mm, adaxial surface densely hirtellous. |
Inflorescences | spikes 1–3, ovoid or ± digitate, 10–30 × 8–26 mm; rays 1–4(–6), 0.5–3(–9) cm; bracts 2–3, approximately horizontal, 1–12 cm × 0.5–2.5 mm. |
spikes turbinate, 10–12 × 6–9 mm, ± as long as wide; rays 6–12, 1–30 cm (longest bract equaling or shorter than longest ray), harshly scabrid; bracts 3–10, horizontal to ascending at 30°, inversely W-shaped, 6–27 cm × 3–6 mm; rachilla persistent, wings hyaline, 0.5 mm wide, covering 1/2 of mature achene. |
Spikelets | 1–6, compressed, oblong-lanceoloid, 5–15 × (2–)2.3–2.8 mm; floral scales (4–)8–24, closely imbricate, laterally yellow to yellowish brown, margins light brown to clear, medially green, laterally ribless, medially 2–3-ribbed, 2-keeled basally, ovate, (1.5–)1.8–2.2 × 1.8 mm, apex obtuse. |
30–60, proximal spikelets reflexed nearly parallel to ray, distal ones spreading, linear, ± terete, 6–8 × 1–1.4 mm; floral scales persistent, 1(–2), appressed, stramineous, often suffused with reddish purple, laterally 4–6-ribbed, ovate-lanceolate, 4–4.5 × 1.4–1.6 mm, apex straight, excurved mucronate or cuspidate; terminal scale spinose. |
Flowers | stamens 3; anthers 0.4 mm, connectives not prolonged; styles 0.5–1 mm; stigmas 0.5–0.8 mm. |
anthers 0.5–1 mm; styles 1.5–2 mm; stigmas 2 mm. |
Achenes | jet black to reddish brown, slightly stipitate, obovoid, 1–1.2 × 0.8 mm, apex apiculate, surface with network of rectangular longitudinally elongate cells and transverse undulations. |
dark brown, narrowly oblong, (2.4–)2.7–2.9(–3.2) × 0.7–0.8 mm, base cuneate, apex obtuse, apiculate, surfaces puncticulate. |
Cyperus flavescens |
Cyperus plukenetii |
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Phenology | Fruiting summer–early fall. | Fruiting summer (Jul–Aug). |
Habitat | Damp, often disturbed soils | Dry sand hills, xeric upland woods |
Elevation | 0–800 m (0–2600 ft) | 0–200 m (0–700 ft) |
Distribution |
AL; AR; CA; DC; DE; FL; GA; IL; IN; KS; KY; LA; MA; MD; MI; MO; MS; NC; NJ; NY; OH; OK; PA; SC; TN; TX; VA; WV; ON; South America; West Indies; Eurasia; Africa
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AL; AR; DE; FL; GA; KY; LA; MD; MO; MS; NC; NJ; OK; SC; TN; TX; VA
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Discussion | North American populations have been distinguished as Cyperus flavescens var. poiformis; their taxonomic separation was not supported by M. L. Corcoran’s (1941) careful study. Plants of Mexico and Central America consistently have purplish rather than yellowish floral scales and may be recognized as C. flavescens var. piceus (Liebmann) Fernald (G. C. Tucker 1983, 1994). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Cyperus plukenetii is distinguished by its tight, burlike spikes, few-flowered spikelets, and densely pubescent culms, leaves, and rays. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 162. | FNA vol. 23, p. 180. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycreus | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | C. flavescens var. poiformis, C. poiformis, Pycreus flavescens | |
Name authority | Linnaeus: Sp. Pl. 1: 46. (1753) | Fernald: Rhodora 47: 110, plate 877. (1945) |
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