Blue Oak Quercus douglasii
Blue Oaks are a medium sized deciduous tree reaching up to over 50 feet tall. Leaves have a irregular sometimes wavy margin that are 1 to 3 inches long and acorns 3/4 to 1-1/2 inch long. In late summer and early fall the leaves will deepen their color to a blueish-green... thus the "blue" oak. Blue Oaks occur only in California most often in areas where temperatures get quite hot. In the central coast ranges they are found inland and are often in grasslands bordering mixed chaparral, pines, and Valley Oak.
From a distance it is hard to identify a Blue Oak from other deciduous oaks (except in late summer when some will take on a blueish cast to the deep green color). It is a medium sized tree that rarely has a trunk over 2 feet in diameter.
Irregular, wavy margins without deep lobes often help distinguish the Blue Oak from the Valley Oak