Pseudotsuga menziesii var. glauca

Interior Douglas-fir or Rocky Mountain Douglas-fir is in the pine or Pinaceae family and is a cousin of coast Douglas-fir. Its natural range is the higher elevation and drier climates from central British Columbia and southwest Alberta in Canada southward through the United States to the far north of Mexico. The name of the interior variety is Pseudotsuga menziesii var. glauca.

The Interior Douglas-fir has been known to reach a height of 65 m and has characteristics of its larger counterpart Coast Douglas-fir growing in a colder and drier climate; thus is grows more slowly and the cones are typically about 2/3ds the size of those on the Coast. Note Pseudotsuga menziesii var. menziesii for detailed defining characteristics.

In addition to having characteristics of a slower growing variety, the interior species also can have a bluish colour in the extremes of its range, particularly as it extends into the southern United States and New Mexico. In these hotter and drier areas, to reduce moisture loss, needles form a thicker wax layer which has a higher refractive index that makes it appear more blue. Note the photos of the "blue" variety of glauca in the photographs, also with its longer three-pronged bracts.