Rhynchospora latifolia
Rhynchospora compressa
sandswamp whitetop
flatfruit beaksedge
arching or erect, leafy-based, distally wandlike, terete, multiribbed.
erect to ascending, leafiest at base, triangular, slender, somewhat stiff.
ascending to spreading, overtopped by scape;
blades linear, proximally flat, 2.5–5 mm wide, apex subulate, trigonous.
exceeded by culm;
basal blades crowded, spreadingexcurved, distal ascending, linear, proximally flat, 3–5 mm wide, apex trigonous, shortsubulate.
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 3–5, compact, the proximalmost widely spaced, turbinate or lobed to hemispheric; leafy bracts setaceous, mostly overtopping clusters.
white, ovoid, 5–7 mm;
fertile scales boatshaped, sharply curved-keeled, 5 mm, apex acute.
redbrown, broadly ovoid, 3–3.5(–4) mm, apex acuminate;
fertile scales broadly ovate to ± orbiculate, 2–2.5(–3) mm, apex rounded to notched, midrib included or shortexcurrent.
perianth absent.
perianth bristles 6, reaching from fruit midbody to tubercle, 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–)2.5–2.8(–3) mm;
body brownish, broadly obovoid to nearly orbicular, 1.5–2 × 1.5–2 mm;
surfaces strongly transversely wavyrugose, intervals rows of vertical, rectangular alveolae;
tubercle conic-subulate, basal rim flaring above short neck on achene.
= 12.
Rhynchospora latifolia
Rhynchospora compressa
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 compressa is very closely akin to R. recognita and even coarser; inflorescence clusters are about as bristly and fertile scales blunter than those in R. recognita. It is less inclined to have an excurrent midrib, and the fruit is flatter. Both species often produce sterile spikelets, sometimes comprising an entire inflorescence.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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