Rhynchospora nivea
Rhynchospora globularis
showy whitetop
globe beakrush, globe beaksedge
erect to spreading-ascending, leafybased, trigonous or compressed, ribbed.
erect or excurved, lax, leafy, slender to wiry.
exceeded by scape;
blades narrowly linear to filiform, 0.2–2 mm wide, apex tapering, trigonous.
overtopped by culm;
basal leaves spreading, twisted, distal longer, erect or ascending;
blades proximally flat, 1–3 mm wide, apex trigonous, subulate, tapering.
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.
spikelet clusters 1–4, proximalmost widely spaced, spikelets elongate, open, turbinate or compactlobed hemispheric;
branches erect to ascending; leafy bracts setaceous, exceeding proximal clusters, exceeded by distal clusters.
white, ovoid, 5–7 mm;
fertile scales several, boat-shaped, 2.5–3.5 mm, keel curved, not sharp.
mostly dark brown to brown, globose to broadly ovoid, (2–)2.5–3(–4) mm, apex acute;
fertile scales broadly ovate to orbiculate, 1.7–2.3 mm, apex obtuse to rounded or emarginate, midrib mostly included, sometimes excurrent as apiculus.
perianth absent.
perianth bristles 6 or less, antrorsely barbellate, of various lengths.
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.
1–3 per spikelet, 1.5–1–8 mm (–2 mm in var. pinetorum);
body tumidly biconvex;
surfaces transversely wavyrugose, intervals of vertically rectangular alveolae or transverserugosity indistinct, surface isodiametrically alveolate or cancellate;
tubercle shortconic to patelliformapiculate.
Rhynchospora nivea
Rhynchospora globularis
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.)
Varieties 3 (3 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Spikelets ovoid; fruit body scarcely transversely wavy rugose, instead with transverse, undulate rows of subisodiametric to very broadly rectangular lattices or alveolae. | var. pinetorum |
1. Spikelets broadly ovoid to subglobose; fruit body distinctly transversely wavy-rugose, intervals composed of irregular rows of vertical, rectangular alveolae. | → 2 |
2. Perianth bristles not extending much beyond fruit midbody; tubercle low conic, distinctly narrower than rounded summit of fruit body. | var. globularis |
2. Perianth bristles extending at least to fruit tubercle, sometimes to tip; tubercle depressed conic or patelliform, apiculate, nearly as broad as more truncate summit of fruit body. | var. saxicola |
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