Rhynchospora latifolia
Rhynchospora grayi
sandswamp whitetop
Gray's beaksedge
arching or erect, leafy-based, distally wandlike, terete, multiribbed.
erect or excurved, leafy, obscurely trigonous, slender, firm.
ascending to spreading, overtopped by scape;
blades linear, proximally flat, 2.5–5 mm wide, apex subulate, trigonous.
shorter than culms;
blades spreading to ascending, linear, proximally flat, 2–4 mm wide, apex involute, then trigonous, subulate.
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 1–4, loose to dense, broadly turbinate, lobed or hemispheric;
peduncles and branches ascending; leafy bracts exceeding proximal, sometimes distal, clusters.
white, ovoid, 5–7 mm;
fertile scales boatshaped, sharply curved-keeled, 5 mm, apex acute.
light redbrown, ellipsoid or narrowly ovoid, 4–5 mm, apex acute to acuminate;
fertile scales broadly ovate, 3.5–4.5 mm, apex acute or acuminate, apiculate.
perianth absent.
perianth bristles mostly 6, reaching from fruit midbody to tubercle tip or beyond, 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, 2.5–3 mm;
body dark brown, broadly, tumidly obovoid, 2–2.5 × 2–2.5 mm, apically buttressed to tubercle;
surfaces finely transversely rugulose or nearly level, with fine transverse rows of pits or low papillae, often appearing nearly smooth;
tubercle lowconic, 0.4–0.6 mm, apiculate.
= 12.
Rhynchospora latifolia
Rhynchospora grayi
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.)
Of all North American species of Rhynchospora, R. grayi appears best adapted to the xeric conditions found in the coarser sands of the longleaf pine-scrub oak–dominated yellow sandhills. Interestingly, it seems seldom to mix with its closest relative, R. megalocarpa, which is more often found in white sandhills.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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