FERNALD. — CARTCES OP SECTION HYPARRHENAE. 465 



t- -1- Perig3-nia horizontally spreading or reflexed when mature, spongy at 

 base, with thin but scarcely winged margins. 

 ++ Spikelets solitary and terminal, pistillate or staminate, or with the 

 flowers variously scattered. 

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



rootstocks (2-i) C- gynocrates. 



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



(25) C. exilis. 

 *-*■ *+ 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-flowered. 



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. onnantha. 

 O O Spikelets with more flowers. 



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

 flowered : 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. anfjiistata. 

 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. sterilis. 



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



5- to 15-flovvered : 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. 

 1- Perigynia 4 mm. or more long, long-beaked. 



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 



