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Picea pungens var. glauca, the Colorado Blue-Spruce, and 

 Picea pungens var. Kosteri, Koster's Blue-Spruce 



The Colorado Blue-Spruce is probably the best known orna- 

 mental evergreen tree, for it is very extensively used. In fact, 

 its unusual beauty has become almost common during recent years 

 through overuse. It is very frequently set in most inappropriate 

 places that fail to show the tree's true value. It is unusually hardy 

 and generally a safe tree to plant. 



A careful observer should notice in any number of these trees 

 and particularly in those about us now that there is variation in 

 the shades of color. During the winter the differences are scarcely 

 apparent but in spring and summer they are very striking. The 

 typical Colorado Spruce, several trees of which stand directly 

 across the path to the west in the next Section, has green foliage. 

 But this tree, as we shall also see in the Douglas Fir, seldom is 

 typically green. It shows a variety of bluish tints and the Colorado 

 Blue-Spruces represent the extremes in this variation. Many 

 years ago an unusually blue variety appeared among some trees 

 that were imported by Koster's Nursery in Holland from this 

 country. It was propagated there by grafting in order to perpetu- 

 ate its color and all the trees that have since been secured by 

 grafting from that original stock are known as Koster's Blue- 

 Spruces. They are the most beautiful of the varieties. It should 

 be understood, however, that all the blue spruces represent merely 

 natural wild differences in degree of color and that one extreme 

 variety has been perpetuated through grafting in the Koster's vari- 

 ety. All the other varieties may arise from seed. 



While the blue spruces are magnificent for the first twenty 

 years of their life they later tend to lose their lower limbs. This is 

 especially true of the grafted forms. A side twig is usually 

 employed for grafting and it has been claimed that the side of 

 the mature tree which corresponds to the lower side of the original 

 slip will first tend to show defects in later years. 



The eight trees which are nearest the apex of this Section are 

 Koster's Blue-Spruces. Those behind them are Colorado Blue- 

 Spruces. 



