FERNALD. — CARICES OF SECTION HYPARRHENAE. 463 
O Perigynia thin and scale-like, barely distended over the achenes, 
e-fourth to one-third broad as Bite 
Perigynia 7 to 10 mm. long - « (1) C. muskingumensis. 
Perigynia shorter . . .... i I 
OO Perigynia firmer, third mage over the aisbatien nearly 
or quite half as broad as | 
+ Perigynia lance-ovate, ea half as broad as Be: 
x Leaves 2.5 mm. broad, or broader . 10) C. mirabilis. 
(For vars. see abov 
xX XX Leaves narrower. 
§ Perigynia RIA about 10-nerved on the inner faces, 
oie 8 pe 12 mm. long: perigynia 4.8 to 6 mm. 
(12) C. tenera. 
Spikelets 5 i” 81 mm. «lone: ‘perigyuls: 4 ie 5 mm. long 
12) C. tenera, var. invisa. 
§ § Perigynia 3- to 5-nerved on the inner Pei mostly les 
than 4 mm. lon : 
Perigynia with ascending inconspicuous tips 
(11) C. straminea. 
Perigynia with divergent conspicuous tips 
(11) C. straminea, var. echinodes. 
++ Perigynia with broad-ovate to orbicular bodie 
X Spike maa and flexuous, with aay clavate-based 
spikelet 
Spikelets Se of close-appressed obscurely 
beaked firm perig (14) C. silicea. 
x eaenee ferrugineous ; ap abrast ‘dhender ienki of the 
read- 
pipes with conspicuous loosely ascending or s 
(12) C. tenera, var. Richii. 
x xX Spike pee fie if tetanus, with brows or ferrugineous 
spikelets 
§Pevggnia 5.6 to 7.7 mm. long, very thin, scale-like, al- 
nsparent: scales blunt . (18) C. soencas 
APE ores less than 5.6 mm. long, firm and op 
(when exceptionally longer in C. alata, with picube 
scales). 
(0 Seales long-acuminate or aristate: perigynia 4 to 5.5 
m. long: achenes oblon 
A Spike green, or finally ‘dull brown: scales lance- 
subulate: perigynia oe 2.8 to 3.7 mm. broad, 
abruptly narrowed at b . . (15) C. alata. 
AA Spike dark brown or seid ee? : perigynia 2.3 to 
mm. broa 
Spikelets closely approximate: scales ovate-lance- 
olate: perigynia ovate, tapering gradually to ~ 
(15) C. alata, var. ferruginea. 
