14 THE GRASSES OF MAINE. 



of the outer layer or epidermis. The fat forms bat 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. 



1 j Spikelets with one flower only (Plate 3) 2 



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



~ j" Flowers arranged in panicles (Plate 19) i 



\ Flowers arranged in spikes (Plate 2) . 



f Flower 

 ( Flowers without awns( Plate 2) 10 



spikes (Plate 2) 1 



'S with awns (Plates 29 and 27) 4 



f Glumes large (Plate 35, a.) 



{ Glumes small and unequal in length 



° 



9 



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



5 -J ling the length of the flowers (Plate 9) Deyeuxia. 



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



( Flow r ering glume without an awn at the end 



6 -] Some species of Agrostis. 

 (Flowering glume with an awn at the end 7 



,_ J Flowers with three stamens 8 



( Flowers with one stamen Cixna. 



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

 8 -] Stipa. 



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



q f Flowers with three stamens Muhlenbergia. 



{ Flowers with two stamens Brachyelytrum. 



1 ~ j 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 



"{ 



