SEDGE FAMILY 115 



Perigynia lance-ovate, the beak shorter than the body; longer bracts less than 1 dm 



long, with yellowish brown margins at base. 



Perigynia nerveless ventrally, tawny at orifice. 37. C. athrostachya 



Perigynia nerved ventrally, hyaline at orifice. 38. C. tenuirostris. ' 



Bracts not conspicuous, rarely slightly exceeding the head. 



Beak of the perigynia flattened and serrulate to tip, often strongly bidentate. 



Scales about the length of the perigynia and nearly of the same width above, 



the perigynia nearly entirely concealed. 

 Head stiff, the spikes approximate. 



Perigynia less than 5.5 mm. long, at most faintly nerved on inner face, 

 loosely ascending; spikes suborbicular; lower bracts prominent, stiff 



39. C. adusta. 

 Perigynia 5.5-7 mm. long, finely many-nerved on inner face, appressed; 



spikes oblong-elliptic; bracts not stiff. 40. C. petasata. 



Head not stiff, flexuous or moniliform. 41. C. aenea. 



Scales shorter than perigynia and noticeably narrower above, the upper part of 



perigynia largely exposed. 



Perigynia subulate to lanceolate, at least 2 1 A times as long as wide. 

 Perigynia subulate, the margin at the base almost obsolete. 



42. C. Crawfordii. 

 Perigynia lanceolate, the margin conspicuous to the base. 



43. C. scoparia. 

 Perigynia ovate-lanceolate or broader, at most twice as long as wide. 



Perigynia narrowly to broadly ovate, 3-4 mm. long. 



Perigynia brownish; spikes closely aggregate, rounded at base. 



44. C. Bebbii. 

 Perigynia green; spikes contiguous to widely separate, usually tapering 



at base. 

 Leaf-blades 2.5 mm. wide or less; perigynia spreading-ascending ; 



culms slender. 45. C. tenera. 



Leaf-blades 2-6 mm. wide (averaging 4 mm.); perigynia appressed- 



ascending; culms stout. 46. C. tincta. 



Perigynia ovate or broader, 3.75-6 mm. long. 



Perigynia thick, abruptly short-beaked; scales little, if at all, tinged 



with brownish red. 47. C. brevior. 



Perigynia thin, tapering to the beak; scales strongly tinged with chest- 

 nut-brown. 48. C. Egglestonii. 

 Beak of the perigynia slender, terete and scarcely, if at all, serrulate towards tip, 



obliquely cut, at times becoming obscurely bidentate. 

 Scales about the length of the perigynia, and of nearly the same width above, the 



perigynia nearly entirely concealed. 

 Culms and head stiff and rigid. 



Culms 1-3 dm. high, in large stools; scales strongly tinged with reddish 



brown; perigynia lanceolate. 49. C. phaeocephala. 



Culms taller, not in large stools; scales lighter-colored; perigynia ovate, 



in age golden yellow at base. 50. C. xerantica. 



Culms slender; head flexuous or moniliform. 



Scales light reddish brown tinged. 51. C. practicola. 



Scales chestnut-brown tinged. 52. C. Piperi. 



Scales shorter than perigynia and noticeably narrower above, the upper part of 



perigynia largely exposed. 



Perigynia thin and membranous, except where distended by the achene. 

 Perigynia 3.5-5 mm. long; culms slender. 



Perigynia lance-ovate, very narrowly margined, spreading; culms 



biennial. 53. C. microptera. 



Perigynia ovate, strongly margined, appressed; culms annual. 



54. C. festivella. 

 Peiigynia 4.5-6 mm. long; culms low. 



Perigynia lanceolate to broadly ovate, nerveless or nearly so on inner 

 face, the beaks conspicuous; culms slender, ascending or decumbent. 



55. C. nubicola. 

 Perigynia narrowly lanceolate, finely nerved on inner face, the beaks 



appressed; culms stiff, erect. 56. C. ebenea. 



Perigynia strongly plano-convex, the walls thick. 



Spikes densely capitate; beak of the perigynia obliquely cut, dark-tipped. 



57. C. pachystachya. 

 Spikes not capitate; beak of the perigynia bidentate, reddish-tipped. 



58. C. Preslii. 



17. CANESCENTES. 



Spikes androgynous ; perigynia unequally biconvex. 59. C. disperma. 



Spikes gynaecandrous ; perigynia plano-convex. 



Lowest bract bristle-like, much prolonged, many times exceeding its 1-5-flowered 



spike; spikes widely separate. 60. C. trisperma. 



Lowest bract much shorter or none; spikes several-many-flowered, the upper approxi- 

 mate. 

 Spikes 2-4, subglobose, closely approximate, forming an ovate or subglobose head; 



perigynia scarcely beaked; scales white-hyaline. 61. C. tenuiflora. 

 Spikes one^many, the lower more or less strongly separate; head elongate; peri- 

 gynia shortly to strongly beaked; scales darker. 

 Perigynia broadest near middle; beak short, smooth or moderately serrulate 



