Rhynchospora debilis
Rhynchospora capitellata
savannah beaksedge
brownish beak-rush, brownish beaksedge, capitate beak rush, rhynchospore à petites têtes
erect to arching or spreading, leafy, ± filiform, ± terete, stiff to rather lax.
arching-ascending, leafy, obtusely trigonous, slender;
principal leaves overtopped by inflorescence;
blades flat, to 3 mm, apex tapering, trigonous.
exceeded by culm;
blades linearfiliform, proximally shallowly concave, 1 mm, apex tapering, trigonous, blunt or broadly acute.
spikelet clusters 1–2, mostly compact, turbinate to hemispheric; leafy bracts setaceous, exceeding spikelet clusters.
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.
dark redbrown, ovoid, 2–3 mm, apex acute;
fertile scales obovate, 1.5–1.7(–2) mm, apex broadly rounded or retuse, midrib excurrent as cusp or mucro to 0.5 mm.
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.
bristles 6 or vestigial, rarely reaching fruit midbody, antrorsely barbellate.
perianth absent.
1–2 per spikelet,1.7–2 mm;
body brown with large pale center, lenticular, broadly obovoid to ± orbicular, 1.2–1.5 × 1.4–1.6 mm;
tubercle flat, triangular, concave-sided, 0.4–0.6 mm, sometimes apiculate.
(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.
Rhynchospora debilis
Rhynchospora capitellata
Rhynchospora debilis is very similar to R. wrightiana except it has smaller spikelet clusters and more depressed fruit tubercles. It is a common invader of cutover and bulldozed low pineland where it assumes a lowspreading habit, its many culms radiating from the common center much like spokes in a wheel.
(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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