572 CYPERACE^E. (SEDGE FAMILY.) 



4. DICLiDIUM. Style 3-cleft; spikehts narrow , terete or nearly so, few- 

 many -flowered, the scales closely oppressed 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- 

 fowered, yellowish-brown 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 Schitlles.) Low grounds and sandy banks, N. Eug. 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. MARtSCUS. Spikelets 1 -4-Jiowered, subterete, usually in dense heads; 

 scales oppressed, 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. Lancastriensis, Porter. Culm (1-2 high) triangular; leaves 

 milter broadly linear ; umbel of 6-9 mostly elongated rays; spikelets i-ery 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 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 -2-Jloti-ered 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, \\" long. 

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



23. C. refractus, Eugelm. 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, l" 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., Avest to 111., Ark., and Tex. Var. 

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

 4-flowered. (C. Wolfii, IToof/.) 111. to Ark., and southward. 



25. C. Torr6yi, Britton. Like the last, but the heads cylindrical or ob- 

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

 west to Tex. 



