554 CTPEHACE^. (SKDGE FAMILY.) 



12. C. phymatddes, IMulil. Culm (l°-2^° high) cqunllinfr the leaves; 

 umlwl often (oiiipound, 4 - 7-rayc(l, much shorter than tlic long involucre ; spikes 

 numerous, li(/Jil chestnut or stniwculw, ucutish, 12 - 30-tlo\vered (4"- 7" long) ; scales 

 dilong, nurrowlj/ scnrious-marf/iufd, nerved, the acutish tips rather loose; achcnium 

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

 Wisconsin, and common southward. 



* « * * Stamens 3 : spikes mirrowhj linear or slender-awl-shapcd, numerous and 



dmseli/ crowded or spiked on the summit of the rays of the open simple or xomi times 

 com/iound umbel, spicadinej or sometimes refleied: scales erect-appnsscd, condu- 

 plicate or kethd, pointhss: joints of the axis of the spike with scali/-wih(jed mar- 

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

 with fibrous roots, or sometimes ajiparentli/ nwre or less perennial from a tuberous 

 or bullions thickened base : no running rootstocks. 

 •*- S{>ikesfiiit, becoming straw-color (^'- 1' long) ; the scales strongli/ conduplicate. 



13. C. Stl'igbsus, L. Culm mostly stout (l°-3<^ high) ; most of the rays 

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

 scales oblong-lanccolatc, several-nerved, much longer than the oblong-lineai 

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

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



••- ■*- Spikes slender and rather awl-shaped, almost terete, at least when mature ; th; 

 scabs less conduplicate and more appressed to the axis. 



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

 rays of the umbel mostly all short and crowded ; spikes 10 - 20-flowered, gelluivish- 

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

 broad scaly margins which embrace the ovate tr'iangular acJunium ; the scales ovate, 

 ohtusish, imbriculeig overlapping. — Low grounds and sandy banks : common. — 

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



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

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

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

 propo'tionally shorter, so as to expose a part of the axis of each joint, the siwces- 

 sive sailes 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. 



* « * * Jie Stamens 3: spikes loosely or somewhat remotely %-\2-flowercd, flattish 



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

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

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

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

 base of the culms. 



16. C. Sehweinitzii, Torr. Culm rough on the angles {l°-2° high); 

 leaves linear ; umbel simple, 4 - 8-rayed ; s/iikes crowded along the U])pcr part of the 

 mostly elongated rays, erect, loose (4"-G" 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. 



