Rhynchospora latifolia
Rhynchospora wrightiana
sandswamp whitetop
Wright's beaksedge
arching or erect, leafy-based, distally wandlike, terete, multiribbed.
slender, ± filiform, leafy, terete to bluntly trigonous.
ascending to spreading, overtopped by scape;
blades linear, proximally flat, 2.5–5 mm wide, apex subulate, trigonous.
shorter than culm;
blades spreading to ascending, ± filiform, proximally flat, 0.5–1(–1.5) mm, apex tapering, trigonous.
terminal, headlike clusters of spikelets, clusters dense, leafy-involucrate;
involucral bracts several, spreading to downcurved, longest 6–13 cm × 5–10 mm, mostly white to midbract, then green, abruptly narrowly linear.
spikelet clusters 1–3, loose to dense, widely spaced to close together, turbinate to hemispheric; leafy bracts setaceous, mostly exceeding spikelet clusters.
white, ovoid, 5–7 mm;
fertile scales boatshaped, sharply curved-keeled, 5 mm, apex acute.
dark redbrown, lanceovoid, 2.5–3.5(–4) mm, apex acute;
fertile scales ovate, 2–3.5 mm, apex acute or acuminate, rarely minutely awned.
perianth absent.
bristles 6, of various length, mostly extending from fruit midbody to tubercle base, antrorsely barbellate.
several per spikelet, 1.5–2 mm;
body yellowish to deep brown, tumidly lenticular, broadly obovoid to orbicular or oblate, 1.5 mm, widest at or toward midbody, margins flowing to tubercle;
surfaces with many fine rows of vertical shallow lattices, their contiguous ends making transverse rows of papillae;
tubercle crescent-based, depressed-triangular, 0.5 mm, apex acute.
1–2 per spikelet, (2–)2–2.5 mm;
body brown with pale center, lenticular, broadly ellipsoid, 1.5–1.7 × 1.2–1.3 mm, surfaces nearly smooth or very finely cancellate;
tubercle flat, triangular with short-oblong, blunttipped nose, or triangularsubulate, 0.5–0.8 mm.
= 12.
Rhynchospora latifolia
Rhynchospora wrightiana
A specimen collected near Tullahoma, Tennessee, reported as Dichromena latifolia (A. Gattinger 1901), was later destroyed by fire. I did not see the specimen, nor was a description of it published. Because extant populations of the similar Rhynchospora colorata are just over the border in Alabama, that species is likely to have been the one found by Gattinger.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The morphologic boundary between Rhynchospora wrightiana and R. fascicularis (particularly morphs of R. fascicularis referred to R. fascicularis var. distans) is difficult, as recent annotations of the material testify. It is best to consider R. wrightiana as a lower, distinctly filiformleaved entity with darker brown, shorter spikelets and shorter fruit. Kükenthal’s concept of R. wrightiana appears to include a considerable amount of R. fascicularis var. distans.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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