THE GRASSES 



For the sake of those who wish to use the keys and 

 attempt to determine the species of grasses here listed for 

 New Mexico, the following description of the grasses is 

 inserted, and, if used with the diagram and its explanation, 

 even a novice may hope to determine most of the species of 



the State. 



There are many kinds of grasses (about 3500 species in 

 all) and they are scattered almost all over the earth. New 

 Mexico has representatives of 9 tribes and 72 genera in the 

 235 and more species here listed. They vary in size from small 

 annuals an inch or two high to great reeds 10 to 15 feet high 

 within our range, while in other localities the giant bamboos are 

 almost tree-like in proportions and live many years. Most 

 grasses are low plants, from a few inches to 3 or 4 feet tall, 

 sometimes growing as single stems though mostly in clumps 

 or bunches of several stems together. Many of them spread 

 by means of underground stems called rootstocks or rhizomes 

 or by prostrate rooting stems called runners. Some of the 

 "bunch grasses" spread by growing only on the outside of the 

 "bunch" and dying ofT in the middle. All the sod forming 

 grasses have some method of spreading either slowly or 



rapidly. 



The stems of grasses (called culms to distinguish them 

 from the stems of other plants) are mostly hollow (fistulous) 

 and have thickened solid places at approximately equal dis- 

 tances (nodes) from which the leaves begin to grow. The 

 base of each leaf is a flat portion folded around the culm for 

 some distance, often more than the distance between the nodes 

 (internodes). This sheathing portion is called the sheath. At 

 the top of the sheath there is usually a small thin, colorless 

 projection or ring-like growth seeming to be a mere continu- 

 ation of the sheath beyond the base of the leaf blade. This 



