Rhynchospora caduca
Rhynchospora chalarocephala
anglestem beaksedge
loosehead beaksedge
erect or ascending, leafy, trigonous.
erect to ascending-arching, slender, nearly terete, multiribbed.
exceeded by culm;
blades linear, proximally 4–7 mm wide, apex trigonous, tapering.
terminal and axillary;
clusters 3–6, mostly dense, narrowly to broadly turbinate, branches ascending; leafy bracts exceeeding proximalmost inflorescences.
spikelet clusters 3–7, widely spaced, clusters loosely turbinate to hemispheric, to 1.3 cm wide.
rich brown, ovoid, (3–)4–5 mm, apex acuminate;
fertile scales ovate, 2.5–3.5 mm, apex acuminate, midrib included or shortexcurrent.
brown to pale red-brown, lance-fusiform, 3–5.5 mm;
fertile scales elliptic, 2.5–4 mm, acute, midrib short-excurrent.
perianth bristles mostly 6, exceeding tubercle tip.
perianth bristles 6, ± equaling tubercle.
mostly 3–4 per spikelet, 2–2.2 mm;
body brown on short pedicellar (to 0.3 mm) stalk, broadly obovoid, lenticular, 1.3–1.5 × 1–1.5 mm, surfaces transversely rugulose, vertically finely striate and rectangularalveolate;
tubercle compressed, triangular acuminate, 0.5–0.8 mm, edges setulose.
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 caduca
Rhynchospora chalarocephala
Rhynchospora caduca has its closest relationships with the even more robust R. odorata Grisebach, on the one hand, and the swampinhabiting, more slender, and rhizomatous R. mixta Britton ex Small, on the other. Intergrades with R. odorata appear in Alabama and northwest Florida; intergrades with R. mixta appear where ranges overlap in both the Atlantic and Gulf coastal plains.
(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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