CiiVKRACEM. 393 



Marshes and swamps. N. Y. and Mass. to Geor. July. %. — Culms very 

 numerous, s.ender, diffuse or recurved, prostrate. (ScaZes membranaceous, red- 

 dish-brown on the sides. Achenium light brown. Intermediate Spike Rush. 



7. E. obtusa Schuites : culm terete or slightly compressed, spongy ; spike 

 globose-ovoid, many-flowered ; scales very obtuse ; bristles 6, longer than 

 the obovate lenticular achenium ; tubercle dilated at base. Scirpus capitatus 

 Linn. 



Bogs and low meadows. Can. to Flor. W. to Ohio. June, July. %. — 

 Culm^ 8 — 15 inches high, cespitose, erect. Spike thick and obtuse, 50—80- 

 flowered. Scales with a green midrib. Obtuse Spike Rush. 



*** Spike ovoid. Scales coriaceous. Bristles 6, rigid. Style Z-cleft. 

 Tubercle nearly as large as the achenium. 



8. E. tuberculosa Brown : culm terete, filiform, striate ; spike globose- 

 ovoid,^ somewhat acute ; scales broad-ovate, very obtuse, loosely appressed ; 

 bristles 6, longer than the oblong and striate achenium ; tubercle large, 

 ovoid, obtuse. Scirpus tuber culosus Mich. 



Sandy swamps. N. Y. and Mass. to Flor. and Louis. Aug. %.—Culm 8 — 12 

 inches high, clothed at base with 1 or 2 sheaths. Spike 12 — 16-flowered. Scales 

 pale green, or whitish mixed with brown. Large-tuhercled Spike Rush. 



**** Spike ovoid or elongated. Scales membranaceous. Bristles 1 — i, 

 slender, rarely none. Achenium roundish or triangular. 



9. E. acicularis Broton: culm setaceous, angular; spike ovoid, acute, 

 few-flowered ; scales oblong, rather obtuse ; bristles 4, slender, shorter than 

 the obovate achenium ; tubercle minute, Scirpus acicularis Linn. S. cap- 

 illaceus Mich. 



Margins of ponds. Hudson's Bay to Flor. June, Jtily. %'i — Culm 2 — 8 

 inches long, cespitose, slender. Spike 3 — 8-flowered. Scales greenish with a 

 purple stripe. Capillary Spike Rush. 



10. E. tenuis Schuites : culm filiform, angular, the sides concave ; spike 

 elliptic, acute at each end ; scales ovate, obtuse ; bristles 2, 3, or none ; 

 achenium obovoid-triangular, rugose ; tubercle minute, triangular. Scirpus 

 tenuis Willd. 



Swamps and wet meadows. Can. to Car. W. to Ark. July. %. — Culm 

 8 — 12 inches long, very slender, with one or two purple sheaths at base. Spike 

 when young somewhat obtuse. Scales dark chestnut color, with the margins 

 white. Slender Spike Rush. 



11. E . melanocarpa Torr.: culm compressed, sulcate ; spike oblong or 

 cylindric-oblong ; scales ovate, obtuse, membranaceous; bristles 3 — 4, 

 slender, mostly as long as the somewhat turbinate and obtusely triangular 

 achenium ; tubercle broad, triangular, short-acuminate. 



Borders of swamps. N. Y. to Geor. May, June. %.. — Culm \2 — 18 inches 

 high, tough, sulcate. Spikes 4 — 6-lines long, thick, many-flowered. Bristles 

 sometimes very short. Black-fruited Spike Rush. 



***** Spike compressed, often somewhat distichmts. Scales membranaceous. 

 Bristles slender. Style 3-clefi. Achenium triangular. 



12. E. pigmeea Torr. : culm setaceous or acicular, much compressed and 

 sulcate ; spike ovate-compressed, few-flowered ; scales ovate ; bristles (» 



17* 



