104 CYPERACEAE 



internode below. Flowers perfect. Perianth of 6-9 retrorsely barbed bristles. 

 Stamens 3. Style persistent as a beak on the top of the achene. Stigmas 2, 

 Achenes linear-oblong. 



1. D. axundinaceum (L.) Britton. Stem stout, 3-10 dm. high; leaves 

 numerous, flat, 2-8 cm. long, 4-8 mm. wide, spreading; lower sheaths bladeless; 

 spikelets 12-25 mm. long, about 2 mm. wide, 6-12-fiowered; glumes lanceolate, 

 acuminate, strongly nerved, BrowTiish; bristles longer than the achenes. D, 

 spalhaceum Fers. Wet places: Newf. — Fla.— Tex. — Ore. — B.C.; C. Am. Plai?i. 

 Jl-0. 



2. CYPERUS L. Galing-ile, Nut grass. 



Sub-scapose perennials or annuals. Leaves basal; blades narrow, grass-like. 

 Scapes in our species simple, triangular, with one or more bracts at the summit, 

 subtending a simple or compound, umbellate or capitate inflorescence; rays 

 usually very unequal in length. Spikelets flat to nearly terete. ^ Glumes 2- 

 ranked, concave, conduplicate or keeled. Flowers perfect; perianth none. 

 Stamens 1-3. Styles deciduous from the summit of the achenes; stigmas 2 or 

 3. Achenes without a tubercle. 



Glumes faUing away from ttie persistent racliis of the flat spikelets. 



Style 2-cIeft; achenes lenticular. 1. C. diandrus- 



Style 3-cleft; achenes 3-angled. 



Wings of the rachis none or very narrow. 

 Annuals; stamen 1. 



Glumes awned or mncronate. 2. C. inflexus. 



Glumes acute, neither awned nor mucronate. 3. C. acuminatus. 



Perennials; stamens 2 or 3. 

 ^ Glumes tipped with a curved or bent awn; perennials with a rootstock. 



4. C. Fcndkrianus^ 



Glumes blxmt or mucronate; perennials with a corm-like base. 



Heads oblong; spikelets ascending; stem rough, 5. C. Schweinitziu 

 Heads short; spikelets more or less spreading; stem smooth. 



Gluntes broadly ovate; achenes 1 .5-2 mm. long. 6. C Houghtoni^ 

 Glumes oblong-ovate; achenes 2-2.5 mm. lon^. 7. C. Bushii. 



Wings of the rachis prominent and separating from it as interior scales. 



8. C. eruthrorhizos, 



Spikelets wholly falling away, usually leaving the two lower glumes persistent. 



9. C. strigosus. 



1. C. diandrus Torr. Annual; stems tufted, 5-30 cm. high; leaves about 

 2 mm. wide; bracts usually 3, at least one much exceeding the spikelets; spikelets 

 in terminal capitate clusters, linear-oblong, 8-18 mm, long, flat, many-flowered; 

 glumes ovate, green, brown, or with brown margins, obtuse, 1-nerved; stamens 

 2 or 3; achenes oblong, gray. Marshy places: N.B.—S.C— Colo.—S.D. Plain 

 — Suhmont, Au-0. 



2. C, inflexus Muhl. Stems slender, tufted, 2-15 cm. high; leaves 1-2 mm. 

 wide; bracts 2 or 3, longer than the umbel; spikelets capitate or in 3-rayed, sessile 

 imibels, linear-oblong, 6-10-flowered, 4-6 mm. long; glumes light brown, lance- 

 olate, several-nerved. C aristatus Rottb. Wet sandy soil: N.B. — Fla. — Calif. 

 — B.C.; Mex, Plain — SuhmonL Jl-S. 



3. C. acuminatus Torr. Stems slender, tufted, 5-35 cm. high; leaves 

 usually less than 2 mm. wide, light green; bracts much elongated; spikelets capi- 

 tate, in 2-4-1 ayed umbels, flat, ovate-oblong, 4-8 mm. long; glumes oblong, pale 

 green, 3-nerved, with short, more or less recurved tips. Wet soil: 111. — La. — 

 Calif,— Wash. Plain. Jl-0. 



4. C. Fendleriainus Boeckel. Stem slender, 3-5 dm. high, triangular above, 

 scabrous on the angles; leaves flat, 2-6 mm. wide, scabrous on the margins; 

 bracts 3-6, the longer much exceeding the inflorescence; spikelets spicate, in 

 simple, often subcapitate, few-rayed imabels,' oblong to cylindric, 5-15 mm. long, 

 2-3 mm. thick; glmnes orbicular-ovate, striate, pale greenish brown with brown 

 or yellow margins. Wet places; w Tex. — Colo. — Ariz.; n Mex. Plain — Sub'- 

 niont. Jl-S. 



5. C. Schweinitzii Torr. Stems tufted, rough, 3-7 dm. high; leaves 2-5 

 mm. wide, roiigh-margined; bracts 3-7, erect; spikelets spicate, in 3-9-rayed 

 umbels, flat, linear-oblong, 6-12-flowered, 8-16 mm. long; glumes convex, light 



