A synopsis of the American species of Ctenium. 
JARED G. SMITH. 
WITH PLATE XXIX. 
Artificial key to the species. 
BS Pa sk Pes ea aa ok asa eae 
1, Spikes 3 to 6, awns of the third and fourth glumes three times 
as long as the glumes themselves . . . . C. polystachyum. 
2 Awn of the fourth glume nearly 2 inches, recurved. C. cirrhosum. 
2, Awn of the fourth glume less than 1 inch, straight or simply 
Be Sh SRE k a) LABS eee eg OR egy aes 
3 Nerves of the second glume strongly tuberculate-roughened . 
3 Nerves simply scabrous. . . . Smile’ eG Capanente. 
+ Awn of the fourth glume twice exceeding it . . . . - 5 
4 Awn about equaling or shorter than the fourth glume. . .- 6 
5 Fifth glume twice as long as its awn; spike 4to5inches . . 
. C. planifolium. 
: ay glume equaling its awn; spikes 2 inches . C glandulosum. 
6 wn of the fourth glume about equaling the glume itself 
' Awn of the fourth glume less than half as long as the glume 
aoe . . . €. brachystachyum. 
. C. brevispicatum. 
C. Carolinianum. 
: oe 1% inch long, sens slender : 
‘Spike 2% to 5 inches long, awns stout . 
1. Spikes three to stx. 
go, ENTUM POLYSTACHYUM Balansa Bull. Soc. Bot. de France 
* 244. 1885. 
oe cespitose, two to four feet high; leaves pubescent; 
X€s three to six, digitate-paniculate; spikelets 4-flowered; 
th and fourth glumes 3-nerved, long-ciliate on the lateral 
aioe the middle nerve prolonged into a scabrous awn three 
.. lore times the length of the glume; fifth glume keeled, 
[361] 
