Rhynchospora oligantha |
Rhynchospora curtissii |
|
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featherbristle beaksedge |
Curtiss' beaksedge |
|
Habit | Plants perennial, densely cespitose, knottybased, 20–40 cm; rhizomes absent. | Plants perennial, densely cespitose, 10–30 cm; rhizomes absent. |
Culms | filiform, leafy at base, wiry. |
lax, erect to excurved, leafy toward base, filiform. |
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 scape; blades filiform, distally flattened, channeled, tapering, to 1 mm wide, margins strongly involute, apex blunt. |
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 1–3, laterals widely spaced, all narrowly turbinate, ellipsoid, or ovoid; leafy bracts setaceous, overtopping proximal clusters, often overtopped by terminal ones. |
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. |
erect or ascending, redbrown, lanciform, mostly 4.5–5 mm, apex acute; fertile scales lanceolate, (3–)4–4.5 mm, apex acute, apiculate. |
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(–5) per spikelet; stipe and receptacle 0.1–0.2(–0.3) mm, setose; body brown with pale glassy center, narrowly obovoidellipsoid, lenticular, 1.2–1.5 mm, margins narrow, flowing to tubercle; surfaces very finely lined longitudinally, transversely with wavy lines of tiny pits; tubercle narrowly triangular or slightly concavesided, flattened, 0.7–1.2(–1.5) mm. |
Rhynchospora oligantha |
Rhynchospora curtissii |
|
Phenology | Fruiting spring–summer. | Fruiting summer–fall. |
Habitat | Sands and peats of bogs, depressions in savannas, open pinelands, seeps | Sands and peats of bogs, pineland pond shores, seeps, and low moist savannas |
Elevation | 0–200 m (0–700 ft) | 0–100 m (0–300 ft) |
Distribution |
AL; DC; DE; FL; GA; LA; MS; NC; NJ; SC; TX; VA; Central America; West Indies
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AL; FL; MS |
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.) |
|
Source | FNA vol. 23, p. 218. | FNA vol. 23, p. 234. |
Parent taxa | Cyperaceae > Rhynchospora | Cyperaceae > Rhynchospora |
Sibling taxa | ||
Synonyms | Phaeocephalum curtissii, R. filifolia var. ellipsoidea | |
Name authority | A. Gray: Ann. Lyceum Nat. Hist. New York 3: 212. (1835) | Britton: in J. K. Small, Fl. S.E. U.S., 195, 1327. (1903) |
Web links |