572 CYPERACE.*:. (sedge family.) 



§4. DICLtDIUM. Stifle 3-cleft; spikelets narrow, terete or nearlji so, few- 

 many -flowered, the scales closely appressed and the broad wings of the jointed 

 rhachis enclosing the triangular achene. 



19. C. specioSUS, Vahl. Culm stout, mosdy low (5-20' high); rays of 

 the simple or compound umbel mostly all short and crowded ; spikelets 10-20- 

 flowered, yellowish-broivn at maturity (3-7" long), the short joints of its axis 

 winged with very broad scaly margins which embrace the ovate triangular 

 achene; the scales ovate, obtusish, imbricately overlapping. (C. Michauxianus, 

 Gray, Manual ; not Schultes. ) — Low grounds and sandy banks, N. Eng. to 

 Fla., west to Minn, and Tex. 



20. C. Engelmanni, Steud. Kesembles n. 19; but the spikelets more 

 slender and terete, somewhat remotely 5-lo-flowered, 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 ; achene oblong- 

 linear, very small. — Low grounds, Mass. to Wise, and southward. 



§5. MARISCUS. Spikelets \ -4-flowered, subterete, usually in dense heads ; 

 scales appressed, several-nerved, the lower empty and often persistent after 

 the fall of the rest of the spikelet ; joints of the rhachis winged, enclosing the 

 triangular achene. Perennial. 



* Spikelets slender and acuminate, more or less refracted in usually close urn- 



belled spikes. — Connecting with § 4. 



21. C. Laneastriensis, Porter. Culm (1-2° high) triangular; leaves 

 rather broadly linear; umbel of 6-9 mostly elongated rays; spikelets very nu- 

 merous in short-oblong close heads, soon reflexed, of 3 - 6 narrow scales, the 

 upper and lower empty, twice the length of the linear-oblong achene, which 

 is nearly 1" long. — Rich soil, Peun. and N. J. to Ala. 



22. C. retrofractUS, Torr. Culm and leaves usually minutely downy 

 and rough on the obtusish augles (1-3° high) ; umbel many-rayed; spikelets 

 slender-awl-shaped, very numerous in obovate or oblong heads terminating the 

 elongated rays, soon strongly reflexed, 1 - 2flowered in the middle (3 - 5" long) ; 

 scales usually 4 or 5, the two lowest ovate and empty, the fertile lanceolate 

 and pointed, the uppermost involute-awl-shaped; achene linear, 1|" long. — 

 Sandy fields, N. J. to Fla. and Tex. 



23. C. refractus, Engelm. Culm 1-2° high ; rays usually more or less 

 elongated ; spikelets very slender, in rather loose heads, divaricate or more or 

 less reflexed, 2-4-flowered ; achene linear, 1^" long. — N. J. to N. C. and Mo. 



* * Spikelets very short, blunt, in densely compacted globose or cylindrical heads. 



24. C. OVUl^ris, Torr. Culm sharply triangular (6'-2° high); umbel 

 1 - 6-rayed ; spikelets (.50-100) in a globular head, 3-flowered, oblo7ig, blunt (1^- 

 2" long) ; scales ovate, obtuse, a little longer than the ovate-oblong achene. — 

 Sandy dry soil, southern N. Y. to Fla., west to 111., Ark., and Tex. — Var. 

 ROBUSTUS, Boeckl., is a form with large heads (4-8" long), the spikelets 3- 

 4-flowered. (C. Wolfii, Wood.) — JU. to Ark., and southward. 



25. C. Torr^yi, Britton. Like the last, but the heads cylindrical or ob- 

 long, spikelets usually 2flowered, and achene linear-oblong. — L. Island to Fla., 

 west to Tex. 



