576 CYPERACE.E. (sedge FAMILY.) 



15. E. compressa, Sullivant. Calms flat, striate, tufted, erect (l--2'^ 

 liigh) ; spikelet ovate-oblong, or at length lanceolate, 20 - 2,Q flowered (4-7'' 

 long; ; scales lanceolate-ovate, acute, dark purple with broad white pellucid 

 margins and summit ; achene yellowish, obovate-pear-shaped , obtusely triangu- 

 lar, wrinkled, crowned with a small conical and pointed tubercle ; bristles 1-4, 

 very slender, fragile, shorter than or equalling the achene (sometimes none or 

 a single rudiment). — Wet places, N. Y, and Ont. to Minn, and Mo. 



16. E. melanoearpa, Torr. C«/?nsyZa«e/iec?, grooved, wiry, erect (9« 

 18' high) ; spikelet cflindrical-ovoid or oblong, thick, obtuse, densely many-flow- 

 ered (3 -6" long); scales closely many-ranked, roundish-ovate, very obtuse, 

 brownish with broad scarious margins ; achene smooth, obovate-top-shaped , ob- 

 tusely triangular, the broad summit entirely covered like a lid by the flat depressed 

 tubercle, which is raised in the centre into a short abrupt triangular point ; 

 bristles often obsolete ; achene soon blackish. — Wet sand, Mass. to Fla. 



17. E. tricostata, Torr. Culms flattish (1 -2° high) ; spikelet soon cylin- 

 drical, densely many-flowered (6-9" long), thickish ; scales ovate, very obtuse, 

 rusty broAvn, Avith broad scarious margins ; achene obovate, with 3 prominent 

 thickened angles, minutely rough-wrinkled, croivned with a short-conical acute 

 tubercle ; bristles none. — X. J. to Fla. 



18. E. Wolfli, Gray. Culms slender (1° high), from very small creeping 

 rhizomes, -I-edgcd : spikelet ovate-oblong, acute ; scales ovate-oblong, obtuse, 

 scarious, pale purple ; achene pyriform, shining, with 9 nearly equidistant obtuse 

 ribs and transverse ivrinkles betiveen them : tubercle depressed, truncate, more or 

 less apiculate; bristles not seen. — Wet prairies, N. Iowa and S. Minn. 



§ 4. Spikelet more or less flattened , thicker than the slender or capillary culm, 

 feiv - many-flowered ; the thin membranaceous scales somewhat 2- Z-ranked ; 

 style 3-cleft ; bristles of the perianth 3 - 6, fragile or fugacious. Small or del- 

 icate species, differing from the last division chiefly in the flattish spikelets. 



* Tubercle cordracted at its jm\ction with the achene. 



19. E. acicularis, R.Br. Culms finely capillary (2-8' long), wore or 

 less A-angutar; spikelet 3-9-flowered; scales ovate-oblong, rather obtuse 

 (greenish with purple sides) ; achene obovate-oblong, ivith 3-ribbed angles and 

 2-3 times as man if smaller intermediate ribs, also transA'ersely striate, longer 

 than the 3-4 very fugacious bristles; tubercle conical -triangular. — Muddy 

 shores, across the continent. (Eu., Asia.) 



20. B. pygmsea, Torr. Culms bristle-like, flattened and grooved (1 -2 

 high) ; spikelet ovate, 3 - 8-flowered ; scales ovate (greenish), the upper rather 

 acute; achene ovoid, acutely triangular, smooth and shining, tipped with a mi 

 nnte tubercle; bristles mostly longer than the fruit, sometimes wanting.— 

 Brackish marshes, from N. Brunswick to Fla. 



* * Tubercle continuous with the nutlet and not contracted at base. 



21 . E. pauciflora, Link. Culms striate-angled, very slender (3 - 9' high), 

 scarcely tufted, on slender running rootstocks, with a short truncate sheath at 

 base ; scales of the ovate spikelet evidently 2-ranked, chestnut-brown, pointless, 

 all flower-bearing, the two lower larger; bristles 3-6, about as long as the 

 conspicuously beaked triangular achene. (Scirpus pauciflorus, Lightfoot.) — 

 Wet places, N. Y. to N. 111. ar.a Minn., north and westward. (Eu., Asia.) 



