I'KKKNNIAL FOKAC.K CKASSES 3 



grass, and many species of the genus Poa, to which Kentucky 

 blue grass belongs. These two tribes may be distinguished 

 from each other by the fact that the spikelets in the cultivated 

 species of the former are almost always one-flowered, while 

 those of the latter are two or more flowered. In the former, 

 the flowering glume is thin or hyaline and not longer than the 

 outer glumes ; while in the latter, it is thick and chartaceous 

 and is no longer than the outer glumes. For classification of 

 important species, see opposite page. 



3. Duration. While some annuals of the grass family are 

 grown and harvested for forage as millet, oats, barley, and 

 maize those grasses which we use for meadows and pastures 

 are perennial, this character being an essential quality. All 

 perennial grasses increase by new culms arising from the 

 nodes, usually the lower ones, of the culm in more or less chain- 

 like succession. The new culms may be sessile, when the 

 process is similar to that of stooling in the cereal grasses; but 

 in perennial grasses more commonly underground or above 

 ground stolons arise from the underground or above ground 

 nodes. Each stolon may give rise to one or more seed-bearing 

 .culms, each with an independent root system. The latter in 

 turn give rise to other stolons and culms. 



The part arising from the node is of course a branch of 

 the culm from which it grows; but it soon becomes a more or 

 less independent plant by the roots which arise from a node 

 of the branch more or less remote from the culm, or else in 

 the case of rhizomes branches in turn arise from their nodes, 

 which become seed-bearing culms. The point to note is that 

 the habit of the plant, whether creeping or tufted, is dependent 

 upon the distance the roots of the secondary culms are from 

 those of the primary culm. The part between the two culms 

 is called a stolon, whether occurring above, on, or underground, 

 and when such part exists the plant is called stoloniferous. 

 \Yhen the stolon is underground the leaves become modified 



