(hence these are named floivering glumes) . Opposed to each flow- 

 ering glume, with its back turned toward the rachilla, is (usually) 

 a two-nerved, two-keeled bract or prophyllum (the paled) , which 

 frequently envelops the flower by its infolded edges. At the base 

 of the flower, between it and its glume, are usually two very small 

 hyaline scales (lodicules) ; rarely there is a third lodicule between 

 the flower and the palea; stamens, usually three (rarely two or 

 one, or more than three) with very slender filaments and two- 

 celled, usually versatile anthers; pistil with a one-celled, one- 

 ovuled ovary, and one to three, usually two, styles with variously 

 branched, most frequently plumose, stigmas; embryo small, lying 

 at the front and base of the seed, covered only by the thin peri- 

 carp; fruit a caryopsis, rich in albumen. (In Sporobolus and Elm- 

 sine the thin pericarp is free from the seed.) 



There are about thirty-five hundred known species 

 of grasses, varying in size from the moss-like Colean- 

 ilms of the North to the tree-like bamboos of the 

 Tropics, which tower to the height of 100 feet or more, 

 and ranging in distribution from Kerguelen Land on 

 the south to the extreme limit of vegetation beyond 

 the Arctic Circle. There is no order of plants more 

 widely distributed, or existing under a greater diversity 

 of soil and climate, and no other order presents such a 

 A^ast number of individual plants or is so important 

 and directly useful to man. 



The characters emplo}^ed in defining the tribes and 

 genera are usually those presented by the spikelets or 

 inflorescence. While the characters of the order are 

 well defined and clear ly separate it from all other 

 families of plants, the establishment of the several 

 subdivisions is very difficult, and in no case can be 

 based upon a single character alone, but upon a combina- 

 tion of them. There is no tribe or large genus which 

 can be separated or defined absolutely from all others; 

 there are alwa} T s exceptions or intermediate forms 

 connecting them. 



Series A .— PAKIOAOEiE. 



Spikelets one rarely two-flowered; when two-flowered 

 the second or terminal one is perfect, the first or lower 

 one being 1 either staminate or neuter; rachilla articu- 



