156 FOEAGE PLANTS AND THEIR CULTURE 



144. Adaptations. Kentucky blue-grass is adapted 

 primarily to temperate regions of relatively high humidity, 

 but in the arid regions succeeds well under irrigation. It 

 is markedly resistant to cold, never freezing out in the 

 most severe winter weather. During summer heat, 

 however, its growth languishes and, even with abundant 



moisture, shows little vigor 

 during the hot weather 

 of July and August. Its 

 area of usefulness extends 

 farther south than that of 

 timothy, as it survives hot 

 summer weather and makes 

 good pasturage in the fall 



FIG. 13. A spikelet and florets and Spring. It begins 



of Kentucky blue-grass, a, spikelet growth in the spring earlier 



as it appears at maturity; b, the same , 



having the florets spread apart, show- tnan most grasses, and COn- 



ing jointed rachilla; c, back view of tinUCS to grow as late into 



a floret, showing .the lemma (1) ; d, , , ,. n , , 



front view of the floret, showing the the fall as any other grass. 



edges of the lemma (1), the palet (2) Blue-grass prefers well- 



and the rachilla segment (3); e, the , . , , , 



grain or kernel. drained loams or clay 



loams, particularly such as 



are rich in humus. Southward it is especially abundant 

 on limestone soils, where it often grows to the exclusion 

 of other species. The famous blue-grass regions of Ken- 

 tucky and Virginia are of limestone origin. On poor soils 

 it is never abundant, giving way to other grasses like red- 

 top and Canada blue-grass. 



Spillman has pointed out that the distribution of blue- 

 grass in the East closely corresponds with that of the 

 glaciated soils and that southward of this area it is con- 

 fined almost wholly to limestone soils. 



Blue-grass will endure fairly wet soils but not so well 



