Rhynchospora latifolia
Rhynchospora brachychaeta
sandswamp whitetop
West Indian beaksedge
arching or erect, leafy-based, distally wandlike, terete, multiribbed.
erect to excurved, lax, filiform, leafy, ± terete.
ascending to spreading, overtopped by scape;
blades linear, proximally flat, 2.5–5 mm wide, apex subulate, trigonous.
exceeded by culm, ascending;
blades filiform, ± terete, margins strongly involute, apex trigonous, sulcate, tapering.
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 mostly 2–3, sparse to dense, oblong to broadly or narrowly turbinate; leafy bracts setaceous, exceeding clusters.
white, ovoid, 5–7 mm;
fertile scales boatshaped, sharply curved-keeled, 5 mm, apex acute.
pale redbrown, lanceoloid, 3–3.5 mm, apex acute;
fertile scales mostly elliptic, 2–2.5 mm, apex acute, sometimes apiculate.
perianth absent.
bristles mere nubs or 1–2, to 0.3 mm.
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.
mostly 2 per spikelet, 1.5–1.6 mm;
body redbrown with pale center, lenticular, broadly obovoid to orbicular, margins pale, narrow, flowing to tubercle;
surfaces smoothish, or faintly cancellate;
tubercle flattened, triangularsubulate, 0.3–0.5 mm.
= 12.
Rhynchospora latifolia
Rhynchospora brachychaeta
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.)
Rhynchospora brachychaeta is quite possibly adventive; most of its localities in the flora are in disturbed areas near the coast. It is similar to the widespread native R. chapmanii, from which it is distinguished by its more numerous spikelet clusters, the darker spikelets, the achene faces brown with pale centers (rather than pale with brown ends), and the relatively more developed perianth.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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