FERNALD. CARTCES OF SECTION HYPARRHENAE. 465 



+- h- Perigynia horizontally spreading or reflexed when mature, spongy at 

 base, with thin but scarcely winged margins. 

 •w Spikelets solitary and terminal, pistillate or staminate, or with the 

 flowers variously scattered. 

 Stoloniferous ; the filiform culms at most 3 dm. high, from filiform 



rootstocks . . . . (24) C. gynocrates. 



Not stoloniferous ; the wiry culms 2 to 7 dm. high, in caespitose stools 



(25) C. exilis. 

 ++ -w Spikelets 2 to several. 



= Perigynia broadest at base : beak rough or serrulate. 



a. Perigynia at most half as broad as long, finally yellowish, with 



slender beak nearly equalling the body : scales pointed. 



1. Perigynia ovate, 3 or 4 mm. long. 

 O Spikelets at most 12-flovvered. 



Spike 1 to 3 cm. long, the 2 to 6 spikelets subapproximate 



(26) C. echinata. 

 Spike 2 to 6 cm. long, the 2 to 4 spikelets very remote, the 

 terminal with a clavate base 0.5 to 1 cm. long 



(26) C. echinata, var. ormantha. 

 O O Spikelets with more flowers. 



Leaves 1 to 2.5 mm. broad : spikelets scattered, 12- to 20- 

 f owered : perigynia less than half as broad as long 



(26) C. echinata, var. excelsior. 

 Leaves 2 to 4 mm. broad : spikelets mostly approximate, 15- 

 to 40-flowered ; perigynia half as broad as long 



(26) C. echinata, var. cephalantha. 



2. Perigynia lanceolate or ovate-lanceolate, 2.5 to 3 mm. long : spike 



of 2 to 6 approximate spikelets (26) C. echinata, var. angustata. 



b. Perigynia more than half as broad as long, firm, brownish or dark 



green, the beak one-fourth to one-half as long as the body. 



1. Scales sharp-pointed : leaves 2.5 to 4.5 mm. broad : spike 1.5 to 3.5 



cm. long ; spikelets 15- to 50-flowered : coarse plant (27) C. stcrilis. 



2. Scales blunt : leaves narrower : spike 1 to 2 cm. long ; spikelets 



5- to 15-flowered : slender plants. 



Leaves 1 to 2 mm. broad : perigynia faintly nerved or nerve- 

 less on the inner faces (28) C. interior. 



Leaves narrower : perigynia strongly nerved 



(28) C. interior, var. capillacea. 

 = = Perigynia broadest near the middle, less than 2 mm. broad, very 

 thin and conspicuously nerved, with short smooth beak : spikelets 



remote (29) C. seorsa. 



* * Perigynia not thin-winged, ascending from the first, plano-convex. 

 t- Perigynia 4 mm. or more long, long-heaked. 



Spikelets lanceolate, in a loosely linear-cylindric spike : perigynia 1 to 

 1.3 mm. broad, strongly nerved : scales oblong : leaves 1 to 2.5 mm. 



broad (33) C. bromoides. 



Spikelets ovate, in flexuous spikes, the lowest very remote : perigynia 

 1.6 to 1.9 mm. broad, faintly nerved or nerveless : scales ovate : leaves 



2 to 5 mm. broad (34) C. Deweyana. 



vol. xxxvii. — 30 



