Rhynchospora brachychaeta
Rhynchospora chalarocephala
West Indian beaksedge
loosehead beaksedge
erect to excurved, lax, filiform, leafy, ± terete.
erect to ascending-arching, slender, nearly terete, multiribbed.
exceeded by culm, ascending;
blades filiform, ± terete, margins strongly involute, apex trigonous, sulcate, tapering.
spikelet clusters mostly 2–3, sparse to dense, oblong to broadly or narrowly turbinate; leafy bracts setaceous, exceeding clusters.
spikelet clusters 3–7, widely spaced, clusters loosely turbinate to hemispheric, to 1.3 cm wide.
pale redbrown, lanceoloid, 3–3.5 mm, apex acute;
fertile scales mostly elliptic, 2–2.5 mm, apex acute, sometimes apiculate.
brown to pale red-brown, lance-fusiform, 3–5.5 mm;
fertile scales elliptic, 2.5–4 mm, acute, midrib short-excurrent.
bristles mere nubs or 1–2, to 0.3 mm.
perianth bristles 6, ± equaling tubercle.
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.
1 per spikelet, (2.5–)2.7–3.3(–3.5) mm, body pale brown with yellowish center, ± broadly oblong-obovoid distal to stipe, lenticular, 1.5–2 × 0.8–1 mm;
tubercle narrowly triangularsubulate, (1–)1.2–1.5(–2) mm, less than 0.5 mm wide at base.
leaves exceeded by culm;
blades flat, linear, 1–2 mm wide, apex tapering, trigonous.
Rhynchospora brachychaeta
Rhynchospora chalarocephala
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.)
Some specimens of Rhynchospora chalarocephala are very difficult to distinguish from R. microcephala, and unquestionably intergrades occur in peninsular Florida and the Gulf southern coastal plain. Rhynchospora chalarocephala tends to have longer, paler, narrower spikelets in looser clusters; the dilated part of the fruit body has a narrower, more oblong outline; and the tubercle is both narrower with a narrower base and longer (mostly 1–1.5 mm versus 0.9–1.2 mm in R. micro-cephala). Most material is easily sorted because R. chalarocephala has paler spikelets in turbinate to hemispheric clusters; the dark brown spikelets of R. microcephala are in globose heads.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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