Colorado blue spruce, or blue spruce, is an attractive tree often used for Christmas trees or as ornamentals, particularly in the eastern United States and Europe.  Leaves (needles) are 1-1 1/2 inches long on lower branches but somewhat shorter on upper branches. They are 4-sided and have a very sharp point on the end. 

Blue spruce is finding increasing popularity as a Christmas tree as a result of its symmetrical form and attractive blue foliage.

Picture and facts courtesy of The National Christmas Tree Growers Association.