164 FLORA. 



rachis separating as a pair of hyaline interior scales; stamens 3; style 3-cleft; 

 achene sharply 3-angled, oblong, pointed at both ends, pale, one-half as long as 

 the scale. In wet soil, S. Ont. to Mass, and Fla., west to Neb., Kans., Tex. and 

 Cal. Aug. -Oct. 



19. Cyperus Halei Torr. KALE'S CYPERUS. (I. F. f. 561.) Annual; culm 

 stout, 0.6-1 m. tall, about equalled by the leaves. Leaves 6-8 mm. wide, very 

 rough-margined, those of the involucre 5-8, much elongated; umbel compound, 

 several-rayed; spikes cylindric, sessile or very nearly so, exceedingly dense, 1-2.5 

 cm. long; spikelets very numerous, linear, 3-5 mm. long, I mm. wide, spreading; 

 scales brown, keeled, indistinctly 5 -nerved, oblong, mucronulate, separating from 

 the rachis at maturity, the wings of the rachis separating as a pair of hyaline 

 scales, as in the preceding species; stamens 3; style 3-cleft; achene 3-angled, 

 minute. In swamps, S. Mo. to Tenn., La. and Fla. July-Sept. 



20. Cyperus speciosus Vahl. MICHAUX'S CYPERUS. (I. F. f. 562.) An- 

 nual; culms usually tufted, 10-40 cm. tall, reddish toward the base. Leaves 

 rough-margined, 3-5 mm. wide, the midvein prominent; leaves of the involucre 

 much exceeding the umbel; umbel 3~7-rayed, the primary rays 2-15 cm. long; in- 

 volucels narrow; spikelets subterete, very narrowly linear, 825 mm. long, less 

 than 2 mm. thick, io 3O-flowered, falling away from the axis at maturity; scales 

 dull brown, thin, appressed, ovate, obtuse, faintly 3~5-nerved on the back; rachis- 

 wings broad, clasping the achene, persistent; stamens 3; style 3-cleft, slightly ex- 

 serted; achene pale, 3-angled, about one-half as long as the scale. In marshes, E. 

 Mass, and R. I. to Ohio and Minn., Fla., Tex. and Cal. July-Sept. 



Cyperus specifcsus ferrugine'scens (Boeckl.) Britton. Scales spreading or slightly 

 recurved, reddish. Mo. to Tex. and N. Mex. 



Cyperus specibsus pslrvus (Boeckl.) Britton. Culm 2-7 cm. high ; umbel very simple, 

 generally of but a single cluster of short spikelets. Mo. to N. Mex. 



21. Cyperus ferax Rich. COARSE CYPERUS. (I. F. f. 563.) Annual, closely 

 related to the preceding species, but with smooth-margined, shorter and broader 

 leaves, those of the involucre sometimes but little exceeding the inflorescence. 

 Umbel often compact, the rays mostly short; spikelets linear, subterete, 10-20- 

 fiowered, 16-25 mm. long, about 2 mm. thick, falling away from the axis at ma- 

 turity; scales ovate-oblong, appressed, imbricated, obtuse, rather firm, green and 

 7-9-nerved on the back, yellowish on the sides; stamens 3; style 3-cleft; rachis 

 broadly winged; achene 3-angled, narrowly obovoid, obtuse. In wet soil, Mo. to 

 Cal. and widely distributed in tropical America. Aug. -Oct. 



22. Cyperus Engelmanni Steud. ENGELMANN'S CYPERUS. (I. F. f. 564.) 

 Annual; culms slender, 15-75 cm. tall. Leaves elongated, 4-6 mm. wide, flaccid, 

 roughish on the margins, those of the involucre 4-6, the longer exceeding the 

 umbel; umbel often compound, the spikelets often densely crowded, very narrowly 

 linear, subterete, 1-2.5 cm. long, 5~i5-flowered; rachis narrowly winged; scales 

 greenish-brown, oblong, obtuse, thin, faintly 3~5-nerved on the back, distant, the 

 successive ones on each side of the spikelet separated by a space of about one-half 

 their length; stamens 3; style 3-cleft; achene linear-oblong, 3-angled, two-thirds 

 as long as the scale. In wet soil, Mass, to S. Ont. and Wise., south to N. J. and 

 Mo. Aug. -Oct. 



23. Cyperus strigosus L. STRAW-COLORED CYPERUS. (I. F. f. 565.) 

 Perennial by basal tuber-like corms; culm rather stout, 0.3-0.9 m. tall. Leaves 

 rough-margined, 4-6 mm. wide, the longer ones of the involucre much exceeding 

 the umbel; umbel several-rayed, some of the primary rays often 10-15 cm. long, 

 their sheaths terminating in 2 bristles; involucels setaceous; heads oblong or 

 ovoid; spikelets flat, linear, 8-19 mm. long, 2 mm. wide or less, 7-15 -flowered, 

 separating from the axis at maturity; scales straw-colored, oblong-lanceolate, sub- 

 acute, strongly several-nerved; stamens 3; style 3-cleft; achene linear-oblong, 

 3-angled, acute, about one-third as long as the scale. In moist meadows, swamps 

 or along streams, Me. and Ont. to Minn, and Neb., south to Fla. and Tex. Aug.- 

 Oct. 



Cyperus strig6sus capit&tus Boeckl. Umbel simple or nearly so; spikelets 8-14 mm, 

 long, densely capitate in subglobose heads. Range of the type. 



