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 Unear-oblong. 



1. D. arundinaceum (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-flowered; glumes lanceolate, 

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

 spathaceiim Fers. Wet places: Newf. — Fla. — Tex. — Ore. — B.C.; C. Am. Plain. 

 Jl-0. 



2. CYPERUS L. Galingale, 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, conduphcate 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 falling away from the persistent racliis of the flat spikelets. 



Style 2-cleft; aclienes lenticular. I. C. diandrus. 



Style 3-cleft; achenes .3-angled. 



Wings of the rachis none or very narrow. 

 Annuals; stamen 1. 



Glumes awned or mucronate. 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. Fcndlerianus, 

 Glumes blunt or miicronate; perennials with a corm-like base. 



Heads oblong; spikelets ascending; stem rough. .5. C. Schweinitzii. 

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



Glumes broadly ovate; achenes 1 .,5-2 mm. long. 6. C. Houghtoni. 

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

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



8. C. crt/throrhi:os. 

 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 si^ikelets; 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 

 — Suhmonl. 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 innbcl; spikelets cajiitate or in 3-rayed, ses.sile 

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

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

 — 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-iayed umbels, flat, ovate-oblong, 4-8 mm. long; glumes oblong, pale 

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

 Cahf.— Wash. Plain. JI-0. 



4. C. Fendlerianus 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 umbels, oblong to cylindric, 5-15 mm. long, 

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

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

 mont. Jl-S. 



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

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

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



