Scirpus pallidus
Scirpus cyperinus
cloaked bulrush, pale bulrush
common woolly bulrush, common woolsedge, cottongrass bulrush, scirpe souchet, wool grass
fertile ones upright or nearly so;
nodes without axillary bulblets.
fertile ones upright or nearly so;
nodes without axillary bulblets.
5–10 per culm;
sheaths of proximal leaves green or whitish;
proximal sheaths and blades with septa many, conspicuous or not;
blades 20–55 cm × 8–16 mm.
5–10 per culm;
sheaths of proximal leaves green to red-brown;
proximal sheaths and blades with septa few to many, conspiucuous or inconspicuous;
blades 22–80 cm × 3–10 mm.
terminal, rarely also with 1 lateral inflorescence from distal leaf axil;
rays ascending or divergent (commonly both in same inflorescence), smooth throughout or scabrous at distal end, rays without axillary bulblets;
bases of involucral bracts green or margins brown, not glutinous.
terminal;
rays ascending or sometimes spreading, scabrous throughout or main branches smooth proximally, rays without axillary bulblets;
bases of involucral bracts reddish brown, brownish, or blackish, not glutinous.
aggregated in a few dense clusters of 12–130 (largest cluster with 40–50+), spikelets sessile, narrowly ovoid, 4–5 × 1.8–2.3 mm;
scales black or brownish black with pale midribs, elliptic to ovate, 1.6–2.8 mm, ending in terete or flat awn 0.4–0.6(–1.2) mm.
in dense cymes of 2–15, central spikelet of each cyme sessile, others sessile or pedicellate, spikelets broadly ovoid, ovoid, or sometimes cylindric, 3.5–8 × 2.5–3.5 mm;
scales reddish brown, brownish, or blackish, ovate or narrowly ovate to oblong-ovate or oblong-elliptic, 1.1–2.2 mm, apex apiculate or short-mucronate, apiculus or mucro to 0.1 mm.
perianth bristles persistent, 6, rather stout, straight or curved, longest bristles equaling achene, with retrorse, thin-walled, round-tipped teeth in distal 0.3–0.5, enclosed within scales;
styles 3-fid.
perianth bristles persistent, 6, slender, contorted, much longer than achene, smooth, projecting beyond scales, mature inflorescence appearing woolly;
styles 3-fid.
pale brown or almost white, oblong-elliptic to elliptic or obovate in outline, plumply trigonous or plano-convex, 0.8–1.2 × 0.4–0.6 mm.
whitish to very pale brown, elliptic or obovate in outline, plumply trigonous or plano-convex, 0.6–0.9 × 0.3–0.5 mm.
= 56.
= 66.
Scirpus pallidus
Scirpus cyperinus
Scirpus pallidus has been confused with S. atrovirens. The awned rather than mucronate scales distinguish S. pallidus from all similar species. The perianth bristles are similar to those of S. atrovirens; the scales of S. pallidus are almost always black, rather than brownish as in S. atrovirens. Inflorescences of S. pallidus consist of relatively few, large glomerules (the largest glomerule in the inflorescence usually has 50 or more spikelets). Some individuals of S. atrovirens may have glomerules with as many as 65 spikelets.
Scirpus pallidus occasionally hybridizes with S. atrovirens.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Scirpus cyperinus is extremely variable. A form common in the northern part of its range, south to Iowa, northern Ohio, Maryland, and (in the Appalachians) North Carolina and Tennessee, has bases of the involucral bracts and the involucels blackish, the spikelets sessile or nearly so in glomerules, and the scales relatively short, ovate, and brownish. This form has often been treated as S. cyperinus var. pelius. A more robust southern form, extending north to southern Missouri and Illinois, Kentucky, Virginia, and (along the coast) New Jersey and Massachusetts, has the bases of the involucral bracts and the involucels reddish brown, the spikelets mostly solitary, and the scales relatively long, narrowly elliptic, and reddish brown. This form has often been treated as a distinct species, S. rubricosus (or under the illegitimate name S. eriophorum Michaux). These two morphologies intergrade so extensively that it is not practical to recognize them taxonomically at any rank.
Scirpus cyperinus often hybridizes with S. atrocinctus and S. pedicellatus, forming hybrid swarms. Some plants appear to have characteristics of all three species; the names Scirpus atrocinctus var. grandis Fernald and S. atrocinctus forma grandis (Fernald) D. S. Carpenter are based on such a specimen.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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