16. S. atròvirens, Muhl. Leaves somewhat more rigid; spikelets dull greenish-brown, densely conglomerate (10–30 together) into close heads, these also usually densely clustered in a less compound panicle; scales pointed; bristles sparsely and strongly downwardly barbed above the middle, naked below, nearly straight, as long as the conspicuously pointed and obovate-oblong triangular achene.—Wet meadows and bogs, N. Scotia and N. Eng., west to Minn., Kan., and the Pacific.
17. S. polyphýllus, Vahl. Culm usually more leafy; spikelets yellow-brown, ovate, becoming cylindrical, clustered 3–8 together in small heads on the short ultimate divisions of the open decompound umbel; scales mucronate; bristles 6, usually twice bent, soft-barbed toward the summit only, about twice the length of the achene.—Swamps and borders of ponds, western N. Eng to N. C., west to Minn, and Ark.
9. ERIÓPHORUM, L. Cotton-Grass. ([Pl. 3.])
Bristles naked, usually very numerous, often silky and becoming greatly elongated. Otherwise as in Scirpus.—Spikelets single or clustered or umbellate, usually involucrate with erect scale-like bracts, upon a leafy or naked stem; scales membranaceous, 1–3-nerved. Style very slender and elongated, 3-cleft. Achene acutely triangular. (Name composed of ἔριον, wool or cotton, and φορός, bearing.)
[*] Bristles 6, rust-colored, becoming tortuous and entangled; culm very leafy, bearing numerous spikelets in an involucrate decompound cymose-panicled umbel.
1. E. lineàtum, Benth. & Hook. Culm triangular, leafy (1–3° high); leaves linear, flat, rather broad, rough on the margins; umbels terminal and sometimes axillary, loose, drooping, the terminal with a 1–3-leaved involucre much shorter than the long slender rays; spikelets oblong, becoming cylindrical (2–4´´ long), on thread-like drooping pedicels; bristles at maturity scarcely exceeding the ovate green-keeled pointed scales; achene sharp-pointed. (Scirpus lineatus, Michx.)—Low grounds, western N. Eng. to Ga., west to Minn. and Mo.
2. E. cyperìnum, L. (Pl. 3, fig. 6–10, under Scirpus.) (Wool-Grass.) Culm nearly terete (2–5° high); leaves narrowly linear, long, rigid, those of the involucre 3–5, longer than the umbel, the rays at length drooping; spikelets exceedingly numerous, ovate, clustered, or the lateral pedicelled, woolly at maturity (1½–3´´ long); the rust-colored bristles much longer than the pointless scales; achene short-pointed. (Scirpus Eriophorum, Michx.)—Wet meadows and swamps, Newf. to Fla., west to Minn. and Iowa. Exceedingly variable in the character and size of the umbel, the typical form having the spikelets mostly clustered in small heads.—Var. láxum has the spikelets scattered, the lateral long-pedicelled.
[*][*] Bristles 6, crisped, white; spikelet single, small; involucre of one short bract.
3. E. alpìnum, L. (Pl. 3, fig. 1–6.) Culms slender, many in a row from a running rootstock (6–10´ high), scabrous, naked; sheaths at the base awl-tipped.—Cold bogs, Lab. to N. Eng., west to Minn. June. (Eu.)
[*][*][*] Bristles very numerous, not crisped, forming dense cottony heads in fruit.