Rhynchospora latifolia
Rhynchospora capitellata
sandswamp whitetop
brownish beak-rush, brownish beaksedge, capitate beak rush, rhynchospore à petites têtes
arching or erect, leafy-based, distally wandlike, terete, multiribbed.
arching-ascending, leafy, obtusely trigonous, slender;
principal leaves overtopped by inflorescence;
blades flat, to 3 mm, apex tapering, trigonous.
ascending to spreading, overtopped by scape;
blades linear, proximally flat, 2.5–5 mm wide, apex subulate, 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.
terminal and axillary, clusters 1–5 or more, compact, turbinate or hemispheric, 1–1.5 cm wide;
peduncles progressively shorter distally on culm;
bracteal leaves mostly exceeding subtended compounds.
white, ovoid, 5–7 mm;
fertile scales boatshaped, sharply curved-keeled, 5 mm, apex acute.
rich deep brown, rarely pale brown, lanceellipsoid, 3.5–4(–5) mm;
fertile scale elliptic, 2.7–3 mm, apex acute or rounded, midrib shortexcurrent or not.
perianth absent.
perianth absent.
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–)2–3(–5) per spikelet, (2–)2.5–3 mm;
body redbrown with pale central disc, stipitate, lenticular, obovoid, 1.2–1.5 × 0.7–1(–1.2) mm, margins pale, wirelike, surfaces slick;
tubercle triangular-subulate, (0.8–)1–1.2(–1.6) mm.
= 12.
Rhynchospora latifolia
Rhynchospora capitellata
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 capitellata occurs infrequently in the lower Gulf coastal plain (in Florida, only north) and intergrades with R. glomerata. Forms with antrorsely barbellate bristles are referred to forma controversa (S. F. Blake) Gale; those with smooth bristles are named forma discutiens (C. B. Clarke) Gale (S. Gale 1944). Occasional forms with trigonous fruits occur.
Bruce Sorrie (pers. comm.) believes that many of the southern coastal plain records for Rhynchospora capitellata are based on examples of a neglected taxon, R. leptocarpa (Chapman) Small (J. K. Small 1933), and he wishes to reinstate it. Occurring in semi-shady moist sites in steepheads, or from seeps and shallows along blackwater streams, the plants are mostly distinguished by the tall, lax habit; the many distant, small clusters of light brown or tan spikelets; and the softer, more lax foliage. Measures of spikelets, fertile scales, perianth, achenes, and fruit tubercles show a strong overlap with those of southern examples of R. capitellata. The long, lax culm habit, the softer and paler foliage, and the paler spikelets could well be ecologic responses, or the plants could indeed represent a geographic variant.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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