208 



BREEDING CROP PLANTS 



sis), Canada bluegrass (Poa compressa), arid redtop (Agrostis 

 palustris) . 



The variability (see Fig. 49) of each of the different species of 

 grasses presents a wealth of material for breeding purposes. 



FIG. 49. Individual timothy plants grown under like conditions. The upper 

 plants are undesirable, one having weak stems and the other lacking vigor. 

 The lower plants are more desirable. They differ in density of plant and number 

 of culms. (Courtesy of Myers.) 



Moreover, the fact that many of them may be conveniently prop- 

 agated as clones facilitates a study of the value of individual 



FIG. 50. Flowers of timothy. 



1. Spike. 



2. Floret a, anther; b, filament; c, branched stigma; d, style; e, ovary; 

 /, outer glume. 



3. Outer glume. 



4. a, feathery stigma; 6, style; c, ovary. 



5. Spikelet showing a, palea; b, floral glume. (After Seal after Trinius and 

 Scribner.) 



Size: 1, $in; 2, 80n; 3, 4, 5, greatly enlarged. ' " 



