Rhynchospora thornei |
Rhynchospora breviseta |
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Thorne's beaksedge |
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Habit | Plants perennial, densely cespitose, 10–20 cm; rhizomes slender, short. | Plants perennial, densely cespitose, knottybased, 20–40 cm; rhizomes absent. |
Culms | lax, filiform, leafy. |
leafy at base, filiform, wiry. |
Leaves | spreading to ascending, exceeding or exceeded by culm; blades 0.2–0.3 mm wide, margins strongly involute or channeled, apex trigonous, tapering, setaceous. |
blades filiform, nearly reaching inflorescence tip or much shorter, to 0.3 mm thick, apex tapering. |
Inflorescences | cluster of cymes 1–2, widely spaced, turbinate, sparse; branches few; foliaceous bracts setaceous, longer than cymes. |
spikelet clusters mostly 2–6, simple or reduced to 1 spikelet, often with 2 capillary branches, one divaricate or reflexed, 1 ascending; leafy bracts single per cluster, filiform, setaceous, with clusters appearing lateral to bracts. |
Spikelets | brown, lanceovoid to fusiform, 2.5–3 mm, apex acuminate; fertile scales ovate, 1.5 mm, apex acute, midrib shortexcurrent. |
pale redbrown, ellipsoidlanceoloid, 5–6(–8) mm, apex acute to acuminate; fertile scales narrowly ovate, 3–5(–6) mm, apex acute, midrib included or shortexcurrent. |
Flowers | perianth absent. |
perianth bristles 6, not reaching past fruit midbody, stubby, plumose to near tip. |
Fruits | 0.9–1 mm; body lustrous pale brown, ellipsoidlenticular, 0.8–0.9 × 0.5–0.6 mm, margins narrow, wirelike; surfaces minutely reticulate; bristles 4–6, the longest from shorter than fruit midbody to fully as long, rarely reaching tubercle tip, minutely antrorsely barbellate; tubercle shortconic, to 0.15 mm. |
3–8 per spikelet, 2–2.5 mm; body light brown to brown, ellipsoid-obovoid, tumidly lenticular, 1.5–2 × 1.6–1.7 mm; surfaces faintly, interruptedly crossrugulose, apically indented under tubercle; tubercle lowconic, 0.5 mm, base flaring, circular. |
Rhynchospora thornei |
Rhynchospora breviseta |
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Phenology | Fruiting late spring summer. | Fruiting spring–summer. |
Habitat | Fluctuating shores of limesink ponds, seeps over calcareous rock | Moist to wet sands or peats of bogs, depressions in savannas, open pinelands, pond shores |
Elevation | 0–200 m (0–700 ft) | 0–200 m (0–700 ft) |
Distribution |
AL; FL; GA; NC |
AL; FL; GA; LA; MS; NC; SC; VA; West Indies |
Discussion | Of conservation concern. Rhynchospora thornei, discovered by Robert Thorne from margins of a limesink pond in southwestern Georgia, has been extirpated at that site. Now the taxon is known from several Alabama and Florida locations and was recently found in eastern North Carolina by R. J. LeBlond. Had S. Gale been sent material of Rhynchospora thornei at the time she was doing her excellent revision, she probably would have treated it as part of her series Rariflorae. Yet without its perianth bristles, R. thornei would be nearly identical to R. divergens and very similar to R. pusilla, both of which belong in subg. Psilocarya. Therefore, it forms an interesting link between subg. Rhynchospora (Eurhynchospora sensu Gale) and subg. Psilocarya. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Rhynchospora breviseta is sympatric with R. oligantha over much of its range; intergrades have not been seen. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 221. | FNA vol. 23. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | R. oligantha var. breviseta | |
Name authority | Kral: Sida 7: 42, fig. 1. (1977) | (Gale) Channell: Rhodora 58: 336. (1956) |
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