Blue Oak or Mountain White Oak TreeThe Blue Oak, or Mountain White Oak (Quercus Douglasii, Hook. and Arn.), is a striking and beautiful feature of the landscape of northern and central California. Silvery grey bark and pale blue foliage, deepened by greenish leaf linings, and lightened by their silvery pubescence! No wonder the blue oak attracts attention whether it stands among the scattered groves of California white oak in the broad valleys-a fine, round-headed tree-or climbs the western slopes of the Sierras till it dwindles to a shrub at an altitude of 4,000 feet. It is strangely variable in the shape of its leaves and fruit. Its leaf may have deep lobes like other white oaks, or it may have scarcely any noticeable waves; some leaves are entire, some have pointed, even spiny-tipped lobes like those of the black oaks. The blue of them, however, is a dependable characteristic; also the silky leaf linings.
The acorns are very numerous, and so vividly green in summer that they often overcome much of the blue of the foliage until they take on their rich, chestnut brown. The nut often bulges above the saucer-like cup as if too large for it; often it is elongated into a pencil shape.
The wood is too brittle and the sap wood too thick for use in building. It is an excellent fuel.