Rhynchospora solitaria
Rhynchospora nivea
onespike beaksedge
showy whitetop
erect to ascending, narrowly linear, wandlike, terete, leafy proximal to middle.
erect to spreading-ascending, leafybased, trigonous or compressed, ribbed.
erect to ascending;
blades proximally flat, 2.5–3.5 mm wide, apex tapering, tip abruptly blunt.
exceeded by scape;
blades narrowly linear to filiform, 0.2–2 mm wide, apex tapering, trigonous.
terminal, cluster of spikelets crowded, broadly turbinate to hemispheric, to 1.5 cm wide; leafy bracts linearsetaceous, slightly exceeding cluster.
terminal, solitary, headlike, dense, white, leafyinvolucrate, hemispheric to globose, 0.5–1.5 cm wide;
involucral bracts (0–)1–4, ascending to recurved, green, (0.7–)2–5(–6) cm × 0.2–2 mm.
orangebrown, lancefusiform, 6–7 mm, apex acuminate;
fertile scales lanceovate, 4–5 mm, apex acuminate with excurved awn to 1 mm.
white, ovoid, 5–7 mm;
fertile scales several, boat-shaped, 2.5–3.5 mm, keel curved, not sharp.
bristles 3–4, some reaching tubercle tip, antrorsely barbellate.
perianth absent.
1–2 per spikelet, 2–2.1 mm;
body brown with paler center, obovoidlenticular, 1.5–1.7 × 1.2–1.3 mm, margins flowing to tubercle;
surfaces finely transversely striate with minute pits;
tubercle lowtriangular, 0.3–0.5 mm.
0.8–1 mm;
body yellow to near black, broadly pyriform-obovoid, tumidly lenticular, 0.5–0.8 × 0.5–0.8 mm, margin narrow, flowing into tubercle;
surfaces transversely sharply wavyrugose, ridges bordered by rows of fine, linear, vertical lattices;
tubercle depressedtriangular, lunate-based, shortbeaked 0.2(–0.3) mm, gray-crustaceous.
Rhynchospora solitaria
Rhynchospora nivea
Of conservation concern.
Rhynchospora solitaria appears to be the least common North American species of Rhynchospora with two of the five given localities apparently lost. The name “solitaria” is deceptive; the plants sometimes form small tufts of culms. The most distinctive feature in the field is the attractive orangebrown color of the narrow, acuminate, bristlescaled spikelets.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Rhynchospora nivea, of the “Dichromena” of North America, is the smallest fruited and most slender and has the fewest and shortest involucral bracts (in some plants the bract is entirely absent). Involucral bracts of R. nivea are almost entirely green.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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