14 THE GRASSES OF MAINE. 



of the outer layer or epidermis. The fat forms but a small percent- 

 age of our grasses, and the digestibility of it has not been accu- 

 rately determined. The nitrogen-free extract contains starch and 

 sugar, vegetable mucilage and a few other substances which have a 

 composition analogous to that of starch, and probably they are 

 equally nutritious. In addition to these, there are varying quanti- 

 ties of gum-like substances and lignine, which are not digestible. 

 The crude fiber is a mixture of cellulose and lignine, and varies with 

 the age of the plant ; the older and more mature contain a larger 

 percentage. The albuminoids, as has been said, comprise the most 

 valuable part of the plant for food. 



SYNOPSIS OF THE GENERA OF GRASSES. 



I Spikelets with one flower only (Plate 3) 2 



\ Spikelets with two or more flowers (Plate 19) 21 



| Flowers arranged in panicles (Plate 19) 3 



{ Flowers arranged in spikes (Plate 2) 13 



o ( Flowers with awns (Plates 29 and 27) 

 { Flowers without awns( Plate 2) 



10 



^ f Glumes large (Plate 35, a.) 5 



{ Glumes small and unequal in length 9 



f Flowers with a copious tuft of hairs at the base, nearlv eqnal- 



5 < ling the length of the flowers (Plate 9) DEYEUXIA. 



( Flowers without hairs at the base of the flowering glume.. . . G 



( Flowering glume without an awn at the end 



6 < Some species of AGROSTIS. 

 (Flowering glume with an awn at the end 7 



| Flowers with three stamens 8 



{ Flowers with one stamen CINNA. 



( Flowers raised above the base of the glumes on a short stem, 



8 -] STIPA. 

 (Flowers not raised above the base of the glumes, ORYZOPSIS. 



9 f Flowers with three stamens MUHLENBERGIA. 



{ Flowers with two stamens BRACHYELYTRUM. 



- ~ ( Glumes present 11 



{ Glumes wanting LEERSIA. 



(" Flowering glume and palea very unequal in length, AGROSTIS. 

 { Flowering glume and palea equal in length or nearly so 12 



