Rhynchospora oligantha |
Rhynchospora pusilla |
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featherbristle beaksedge |
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Habit | Plants perennial, densely cespitose, knottybased, 20–40 cm; rhizomes absent. | Plants perennial, densely cespitose, 15–50(–60) cm; rhizomes absent. |
Culms | filiform, leafy at base, wiry. |
erect or arching, leafy toward base, filiform, terete, wiry. |
Leaves | ascending to erect; blades filiform, nearly terete, or channeled, sometimes compressed, nearly reaching distal inflorescence or much shorter, 0.2–0.3 mm thick, apex subulate. |
overtopped by culm; blades linear to filiform, channeled, 0.3–0.5 mm wide, margins deeply involute, apex setaceous. |
Inflorescences | spikelet clusters 2–6, simple or reduced to 1 spikelet, branches ascending to divaricate or reflexed; leafy bracts single per cluster, filiform, setaceous, with clusters appearing lateral to bracts. |
spikelet clusters 1–2(–3), dense to open, narrowly to broadly turbinate; branches capillary, variously elongate; leafy bracts setaceous, equaling or exceeding clusters. |
Spikelets | pale redbrown, ellipsoidlanceoloid, 5–6(–8) mm, apex acute to acuminate; fertile scales oblongelliptic, convex, acuminate, 3.5–5 mm, apex broadly acute, midrib forming apiculus. |
variously brown, ellipsoid, 2–3 mm, apex sharply acute; fertile scales ovate to nearly orbiculate, rounded, 1.2–1.8 mm, apiculate, convexcupulate, midrib slender, mostly included. |
Flowers | perianth bristles 6, reaching to or slightly past tubercle base, increasingly plumose from middle to base. |
perianth absent. |
Fruits | 1–3 per spikelet, (2.5–)2.7–3(–3.4) mm; body light brown to brown, ellipsoidobovoid, distally conspicuously necked, tumidly lenticular, 1.7–2.5 × 1.5–1.8 mm; surfaces smooth or minutely transversely rugulose; tubercle conicsubulate, 0.5–0.7 mm, base flaring. |
2–3 per spikelet, 0.7–0.9(–1) mm; body pale, obovoid-lenticular, (0.5–)0.6–0.9 × 0.4–0.5 mm, margin wirelike; surfaces transversely rugulose; tubercle buttonlike, depressed triangular, 0.05–0.1 mm, base lunate atop rounded fruit body. |
Rhynchospora oligantha |
Rhynchospora pusilla |
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Phenology | Fruiting spring–summer. | Fruiting summer–fall. |
Habitat | Sands and peats of bogs, depressions in savannas, open pinelands, seeps | Moist sands, peats and silts of low meadows, savannas, bogs, seeps, pond shores |
Elevation | 0–200 m (0–700 ft) | 0–300 m (0–1000 ft) |
Distribution |
AL; DC; DE; FL; GA; LA; MS; NC; NJ; SC; TX; VA; Central America; West Indies
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AL; FL; GA; LA; MS; NC; SC; TX; Mexico; Central America; West Indies |
Discussion | Rhynchospora oligantha is distinguished from other taxa of its complex mostly by the distinctive neck at the achene apex, a feature essentially absent in R. breviseta, its closest relative. Those two species have been heavily impacted by conversion of pine savannas to cropland or pine plantations; even with abandonment or clearing of such land, they are very slow to reoccupy the disturbed sites. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 23, p. 218. | FNA vol. 23, p. 220. |
Parent taxa | Cyperaceae > Rhynchospora | Cyperaceae > Rhynchospora |
Sibling taxa | ||
Synonyms | Phaeocephalum pusillum, R. intermixta | |
Name authority | A. Gray: Ann. Lyceum Nat. Hist. New York 3: 212. (1835) | Chapman ex M. A. Curtis: Amer. J. Sci. Arts, ser. 2, 7: 409. (1849) |
Web links |