CYPEKACEAE 179 



11. Scirpus Califdrnlcus (C. A. Meyer) Britton. Perennial, similar to the next 

 preceding species. Leaves reduced to basal sheaths : involucral bracts short, stoutly subu- 

 late : umbel compound : spikelets 6-10 mm. long, acute, peduncled or some of them sessile : 

 scales brown, ovate, awn-pointed : perianth-bristles shorter than or equalling the achene, 

 short-plumose below : stigmas 2 : achene obovoid, 2 mm. long, plano-convex, nearly white, 

 narrowed above into a short tip, contracted at the base. 



In swamps, Florida to Louisiana, northern Mexico and California, and widely distributed in 

 tropical America. Summer. 



12. Scirpus camp^stris Britton. Perennial. Stems smooth, sharply triangular, 3-5 

 dm. tall. Leaves usually pale green ; blades smooth, 2-4 mm. wide : bracts of the involucre 

 2 or 3, the longer much exceeding the inflorescence : spikelets 3-10, in a dense terminal 

 simple head, oblong-cylindric, 1.5-2.5 cm. long, 5-8 mm. thick : scales ovate, pale brown, 2- 

 toothed at the apex, the midvein excurrent into an ascending or spreading awn : perianth- 

 bristles 1-3, much shorter than the achene, or none : stigmas 2 : achenes lenticular, obovoid 

 or oblong-ovoid, 3-3.5 mm. long, mucronulate, yellow-brown, their surface strongly cellu- 

 lar-reticulated. 



On wet prairies and plains, Manitoba and Minnesota to the Indian Territory, Nevada and Mexico. 

 Spring and summer. 



13. Scirpus robustus Pursh. Perennial by rootstocks. Stem stout, stiff, 3-angled, 

 with flat sides, smooth, 5-14 dm. tall : leaves dark green ; blades smooth, 5-10 mm. wide : 

 involucral bracts 2-4, elongated, similar to the leaf -blades : spikelets ovoid-oblong, stout, 

 1.5-2.5 cm. long, 8-10 mm. in diameter, 6-20 together in a dense terminal cluster : scales 

 ovate, brown, puberulent, thin, the midvein excurrent into an, at length, reflexed awn 3-5 

 mm. long : perianth -bristles 1-6, fragile, shorter than the achene, or none : stigmas 3 : 

 achenes 3-3.5 mm. long, compressed, flat on the face, convex or with a low ridge on the 

 back, obovoid-orbicular, dark brown. 



In salt marshes, Nova Scotia to Florida and Texas. Summer.and fall. 



14. Scirpus sylvaticus L. Perennial by long rootstocks. Stems triangular, stout, 

 smooth, 1-2 m. tall, often overtopped by the upper leaves : leaf -blades 1-1.6 cm. wide, 

 rough on the margins : bracts of the involucre 5-8, the larger often 3 dm. long or more : 

 umbel terminal, very large, sometimes 2 dm. broad, about 3 times compound, the spikelets 

 ovoid or ovoid-oblong, 3-5 mm. long, in capitate clusters at the ends of the raylets : bract- 

 lets of the involucels small, linear or lanceolate : scales ovate-oblong, obtuse, brown with 

 a green center : perianth-bristles 6, downwardly barbed, slightly exceeding the achene : 

 stigmas 3 : achenes oblong, fully 1 mm. long, 3-angled, obtuse, nearly white, mucronulate. 



In swamps, New Hampshire to North Carolina and Georgia. Also in Europe. Summer and fall. 



15. Scirpus atrdvirens Muhl. Perennial by rootstocks. Stems triangular, rather 

 slender, leafy, 5-12 dm. high : leaf-blades elongated, nodulose, dark green, 6-12 mm. 

 wide, one or two of them usually exceeding the inflorescence : spikelets ovoid-oblong, acute, 

 densely capitate at the ends of the rays or raylets : involucels short : scales greenish brown, 

 oblong, acute, the midvein excurrent : perianth-bristles usually 6, downwardly barbed above, 

 naked below, about as long as the achene : stigmas 3 : achenes oblong-obovoid, 1 mm. 

 long, 3-angled, pale brown, dull. 



In swamps, Nova Scotia to Manitoba, Georgia and Louisiana. Summer. 



16. Scirpus polyphyllus Vahl. Perennial by rootstocks. Stems slender, sharply tri- 

 angular, 3-11 dm. tall, very leafy : leaves 3-ranked ; blades 4-6 mm. wide, rough-margined : 

 bracts of the involucre 3-6, the longer commonly somewhat exceeding the inflorescence : 

 spikelets ovoid, about 3 mm. long, capitate at the ends of the raylets : scales ovate, bright 

 brown, mostly obtuse, mucronulate : perianth-bristles 6, downwardly barbed above the 

 middle, twice as long as the achene : stigmas 3 : achenes obovoid, fully 1 mm. long, 3- 

 angled, with a broad face and narrower sides, short-pointed, dull. 



In swamps, wet woods and meadows, Massachusetts to Minnesota, Georgia, Alabama and Arkansas. 

 Summer and fall. 



17. Scirpus Georgianus Harper. Perennial by rootstocks. Stems terete or nearly 

 so, 4-12 dm. tall : leaf-blades smooth, about 2 dm. long, and 1 cm. wide, or the upper ones 

 smaller : bracts of the involucre mostly 3, the largest surpassing the inflorescence : umbel 

 thrice compound : spikelets green, about 3 mm. long, 10-15-flowered, 5-10 in heads : scales 

 orbicular-ovate, about 1.5 mm. long, the toothed awns spreading at the tips, the midrib 

 green, with a whitish keel : perianth-bristles wanting : achenes broadly oblong, about 0.8 

 mm. long, short-beaked. 



In alluvial soil, middle Georgia. Spring and summer. 



18. Scirpus divaricatus Ell. Stems obtusely triangular, rather slender, 6-11 dm. 

 tall : leaf-blades 4-8 mm. wide, rough-margined : umbel decompound, the primary rays 



