OF TENNESSEE. 63 



the distinction of species, but even of genera is often de- 

 termined thereby. 



A nerve often extends over the lamina of the glume or 

 palet, either at the apex, or underneath, from the dorsal or 

 keel-nerve. If this extension is small and delicate, it is 

 named a bristle or bristly apex, if stout and lengthy, an 

 awn or beard. 



3. The common Oat. Avena sativa. L. Panicle large, 

 simple, lax (spikelets remote). Spikelets two-flowered on 

 capillary peduncles. Peduncles and branches rough down- 

 ward. (Roughness felt by motion of the fingers down- 

 ward. 



Glumes larger than the flowers, many-nerved, (eight to 

 ten) thin membranaceous, awnless, persistent. (The glumes 

 holding fast to their pedicels after the grain has fallen off.) 

 Lower palet herbaceous, rounded and awned on the back, 

 above the base, at the point almost bicuspidate ; the upper 

 one bicarinate, awnless. Bicarinate means presenting the 

 form of a Greek omega or transverse section. Awn 

 twisted, geniculate (bent with an angle) one, to one and a 

 half inches long. 



Stamina three, stigma, two plumose, palets investing the 

 long, slightly tufted carvopsis, which is internally marked 

 by a longitudinal furrow, hairy at the point-. 



The seed of grasses (coryopsis) is either free, dropping 

 out from the palets Jike in Sporobolus and Diarrhena, or 

 may be easily detached from the same like in the Wheat. 

 At other times it is invested (firmly wrapped up in) one or 

 both palese, like in Oat, or firmly connected with adhesions, 

 like in the Barley. 



A significant feature in the comparison of grasses affords 

 also the Ligule (see above) whether it be truncate, acute, 

 smooth, hairy, bearded, papillary, etc. Characters are also 

 derived from the root, from the nodes, mode of ramifica- 

 tion by the branching of the .culms. 



