572 CYPERACE^E. (SEDGE FAMILY.) 



4. DICLlDIUM. Style 3-cleft; spikelets narrow, terete or nearly 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, mostly low (5-20' high); rays of 

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

 flowered, yellowish-brown at maturity (3 - 7 /x 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. Resembles n. 19; but the spikelets more 

 slender and terete, somewhat remotely 5-15-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. MAKlSCUS. Spikelets 1 -^-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 um- 



belled spikes. Connecting with 4. 



21. C. Lancastrian sis, 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 \" long. Rich soil, Penn. and N. J. to Ala. 



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

 and rough on the obtusish angles (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 -Z-flowered 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, l" 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, 1J" long. N. J. to N. C. and Mo. 



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



24. C. OVUlaris, Torr. Culm sharply triangular (6'- 2 high); umbel 

 1 -6-rayed ; spikelets (50-100) in a globular head, 3-flowered, oblong, 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.) 111. to Ark., and southward. 



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

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

 west to Tex. 



