Rhynchospora caduca
Rhynchospora plumosa
anglestem beaksedge
plumed beaksedge
erect or ascending, leafy, trigonous.
erect or excurved, filiform to linear.
exceeded by culm;
blades linear, proximally 4–7 mm wide, apex trigonous, tapering.
erect or excurved, shorter than scape;
blades filiform to linear, to 1.5 mm wide, margins involute, apex trigonous, tapering.
terminal and axillary;
clusters 3–6, mostly dense, narrowly to broadly turbinate, branches ascending; leafy bracts exceeeding proximalmost inflorescences.
spikelet clusters 1–several, dense or sparse, when several, either widely spaced or close together, if widely spaced then ovoid to hemispheric, if close together then lobed ellipse or cylinder; leafy bracts filiform, setaceous, overtopping each cluster.
rich brown, ovoid, (3–)4–5 mm, apex acuminate;
fertile scales ovate, 2.5–3.5 mm, apex acuminate, midrib included or shortexcurrent.
light redbrown to deep brown, broadly fusiform to ovoid, (2.5–)3.5–4 mm, apex acute to acuminate;
fertile scale broadly ovate, strongly convex, (1.5–)2–3 mm, apex acuminate to mucronate, midrib excurrent or not.
perianth bristles mostly 6, exceeding tubercle tip.
perianth bristles 6, plumose, reaching at least to fruit midbody, often to tubercle tip.
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(–2) per spikelet, (1.5–)2–2.5 mm;
body redbrown or brown, tumidly obovoid or ellipsoid, sometimes obscurely lenticular, (1.2–)1.3–1.8(–2) × 1–1.5 mm;
surfaces interruptedly crossrugulose;
tubercle narrowly to broadly conic, mostly 0.3–0.5 mm, base flaring, round or indistinctly 2lobed.
Rhynchospora caduca
Rhynchospora plumosa
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.)
Particularly in Gulf Coastal Plain savannas, Rhynchospora plumosa appears to have two distinct morphs: one very densely cespitose with filiform leaves, filiform, arching culms, and spikelets in short, broad, dark brown clusters, and the other morph taller, stiffer, with broader leaves and culms, and longer, sharper, paler spikelets in narrow compounds of clusters. After many attempts to do what others have—namely to create two distinct species—I have had to retrench, because so many intergrades occur.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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