Rhynchospora latifolia
Rhynchospora microcarpa
sandswamp whitetop
southern beaksedge
arching or erect, leafy-based, distally wandlike, terete, multiribbed.
erect to ascending, arching, lax, leafy, slender, trigonous.
ascending to spreading, overtopped by scape;
blades linear, proximally flat, 2.5–5 mm wide, apex subulate, trigonous.
exceeded by inflorescence;
blades ascending to spreading, linear, proximally flat, 1–2(–3) mm wide, apex trigonous, subulate, 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 4–6, mostly dense, widely spaced, narrowly turbinate to ellipsoid;
peduncles erect to ascending, branches ascending; leafy bracts exceeding proximal clusters.
white, ovoid, 5–7 mm;
fertile scales boatshaped, sharply curved-keeled, 5 mm, apex acute.
dark brown, ovoid, 2–3 mm, apex acute;
fertile scales broadly ovate to ± orbiculate, cupulate, 1.5–2 mm, apex rounded to acute, midrib included or excurrent as bristle.
perianth absent.
perianth bristles 6, from vestigial to (rarely) reaching tubercle tip, 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.
2–3 per spikelet, 1.2–1.5 mm;
body brown, obovoid to globose, lenticular, 1–1.2 × 0.8–1 mm, margins narrow, distinct;
surfaces sharply transversely wavyrugose, intervals with rows of vertical, broadly rectangular or ± isodiametric alveolae;
tubercle lowtriangular or triangular, compressed, 0.2–0.3 mm, base lunate.
= 12.
Rhynchospora latifolia
Rhynchospora microcarpa
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.)
Through much of the range of Rhynchospora microcarpa, particularly in limesink or claybased pond areas, is a somewhat shorter series of plants with narrow leaves, tumid fruit 0.7–0.9 mm, often with isodiametric alveolae and depressedtriangular tubercles. Described by S. Gale as R. sulcata, the plants grade into the more typical morphology for R. microcarpa. In peninsular Florida, apparent intergradation with R. elliottii produces some individuals with broad leaves and triangularsubulate tubercles on nearly flat fruits.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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