554 CYPERACE^E. (SEDGE FAMILY.) 



12. C. phymat6d.es, Muhl. Culm (l-2 high) equalling the leaves; 

 umbel often compound, 4 - 7-rayed, much shorter than the long involucre ; spikes 

 numerous, light chestnut or straw-color, acutish, 12 - 30-flowered (4" - 7" long) ; scales 

 oblong, narrowly scarious-margined, nerved, the acutish tips rather loose ; achenium 

 oblong. (C. repens, Ell.) Low grounds, along rivers, &c., Vermont to 

 Wisconsin, and common southward. 



* * * * Stamens 3 : spikes narrowly linear or slender -awl-shaped, numerous and 

 densely crowded or spiked on the summit of the rays of the open simple or sometimes 

 compound umbel, spreading or sometimes reflexed: scales erect-appressed, condu- 

 plicate or keeled, pointless: joints of the axis of the spike with scaly-winged mar- 

 gins partly embracing the achenium : involucre of 3 to several, long leaves : annuals 

 with fibrous roots, or sometimes apparently more or less perennial from a tuberous 

 or bulbous thickened base : no running rootstocks. 

 H- Spikes fiat, becoming straw-color (' - 1' long) ; the scales strongly conduplicate. 



13. C. Strigdsus, L. Culm mostly stout (1- 3 high); most of the rays 

 of the umbel elongated ( 1 ' - 5'), their sheaths 2-bristled ; spikes 10 - 25-flowered, 

 scales oblong-lanceolate, several-nerved, much longer than the oblong-linear 

 achenium. Damp or fertile soil: very common, especially southward. (C. 

 stendlepis, Torr., is of this group and nearly related.) 



<- -i- Spikes slender and rather awl-shaped, almost terete, at least when mature ; the 

 scales less conduplicate and more oppressed to the axis. 



14. C. Michauxianus, Schultes. Culm stout, mostly low (5' - 20' high) ; 

 rays of the umbel mostly all short and crowded ; spikes 10 - 20-fiowered, yellowish- 

 brown at maturity (3" -7" long), the short joints of its axis winged with very 

 broad scaly margins which embrace the ovate triangular achenium ; the scales ovate, 

 obtusish, imbricatefy overlapping. Low grounds and sandy banks : common. 

 Root truly annual : stem seldom bulbous-thickened at the base. 



15. C. Engelmanni, Steud. Resembles the foregoing; but the spikes 

 more slender and terete, somewhat remotely 5 - \5flowered, the zigzag joints of the 

 axis slender and narrowly winged, and the oblong or oval broadly scarious scales 

 proportionally shorter, so as to expose a part of the axis of each joint, the succes- 

 sive scales not reaching the base of the one above on the same side ; achenium oblong- 

 linear, very small. (C. tenuior, Engelm.) Low grounds and sandy banks, 

 Virginia to Wisconsin and southward : also adventive at the Philadelphia Navy 

 Yard. 



***** Stamens 3: spikes loosely or somewhat remotely 6-12-jlowered, fiattish 

 and greenish, several crowded together in one sessile or in a few peduncled heads 

 or dense clusters ; their scales ovate, convex on the back, many-nerved, applied 

 to and little longer than the ovate or obovate and sharply triangular achenium .* 

 perennials, propagating from the hard clustered corms or bulb-like tubers at the 

 base of the culms. 



16. C. Schweinitzii, Torr. Culm rough on the angles (l-2 high); 

 leai'es linear ; umbel simple, 4 - S-rayed; spikes crowded along the upper part of the 

 mostly elongated rays, erect, loose (4" -6" long) ; scales awl-pointed; joints of 

 the axis narrowly winged. Dry sandy shores and ridges, from Lake Ontario 

 to Ohio, Illinois, and northwestward. Flowers rather large. 



