QUERCUS. Widespread, mostly in the Northern Hemisphere. In a better world, we would not need the nursery to provide us with oaks. They would be all around us. However, for all our admiration of them as features of the primeval landscape, and all our use of their names in our settlements (Oakland, Oak Knolls, and the like), we seem to be relentlessly bent on clearing them from the path of advancing civilization. I suppose we will continue to grow them as long as anyone will take them, in the hope that some will find their way into a more or less permanent position. These are a diverse lot, ranging from majestic trees to low subalpine shrubs. They may be evergreen or deciduous, with leaves which range in shape from simple and nearly round to lance-shaped, to the more familiar and distinctive, lobed patterns. They have sometimes showy tassels (catkins, to be proper) of tiny male flowers and inconspicuous, knobby female flowers in spring. However, the female flowers become conspicuous indeed as the acorns of fall. Each has an expanded basal cap, covered with overlapping scales, and a nearly spherical to torpedo-shaped main body. Children (young and old) find them endlessly fascinating. The following natives have a variety of uses in the landscape according to their size, though usually as featured specimens. All thrive in sun and a great variety of soils, with occasional watering once they are established. All of the following are hardy to 10oF. or less, the deciduous types probably to 0oF.
agrifolia. Coast live oak. This is the familiar dark, leafy mass of the coastal hills, usually seen in large numbers where it has survived the bulldozer and the chain saw. It can take many forms, from large shrub to huge (up to 75'), usually widely spreading tree. The trunks are often beautifully contorted, with smooth greyish younger bark and deeply fissured older bark. The leaves are evergreen (or rather, fall as a new crop is produced). They are narrowly oval to nearly round in outline, usually turned under and sharply toothed along the margins. They are softly shiny to lacquered in appearance, deep green above and paler beneath. The acorns are mostly smaller and narrower than those of other native oaks, but make an interesting show. With early, light and careful pruning, it may be maintained at a manageable size even for smaller gardens.
berberidifolia. Scrub oak. This is one of the shrubby oaks. It is usually 8' or less in height, spreading in habit, with attractive silvery grey stems. The leaves are usually around an inch long, broad to narrow, with usually conspicuous, sharp teeth. The acorns are relatively large and prominent in the fall. This is an interesting shrub for wild gardens and mixed plantings.
douglasii. Blue oak. This is the smaller, usually more upright tree you will see after you have left the valley oaks behind and drive into the sun-baked foothills. It grows erect to somewhat fountain-shaped, as much as 60' high but usually much less, with interesting bark made up of many small plates. The leaves are thick but winter-deciduous, blue-green during the growing season and often painted in pastel oranges, yellows and pinks in fall. It is an ideal tree for sunny, open hillsides and other untended areas.
garryana. Oregon oak. This is one of my own favorite oaks, particularly in its smaller mountain form, which we unfortunately do not have. It is a beautiful tree, upright-oval to nearly round in form, with arching branches and attractive ridged bark. The leaves are 3-5" long, flat, with broad, rounded lobes, deep green and shiny above, paler beneath. Fall color includes some exquisite oranges and pinks, as well as the commoner gold shades. With careful pruning, it should be one of the more manageable of the deciduous oaks for home gardens.
kelloggii. Black oak. This is the most dramatic of our deciduous oaks. It grows up to 75' high and wide but is usually half that or less. Often it has a nearly round overall form, with sculptured, arching branches and beautiful dark bark. The leaves are deeply and sharply lobed and up to 8" long. They are often pink to orange in new growth, then deep green when expanded, turning once again, this time to vivid gold, in the fall. They are one of the things that make fall walks in the countryside a treasured experience. The acorns are relatively short and broad. This is a spectacular tree for open hillsides. I suppose it could be controlled forever by pruning, but that would defeat some of its natural majesty.
lobata. Valley oak. Of all the oaks, this one has probably suffered most from the advance of the human wave. It occupies exactly those sites deemed most desirable for settlement-the broad valleys where ample water collects in winter and spring (and causes our settlements endless problems). It is an enormous tree when at its best, with an upright base and arching, fountain-like trunks up to 100' high, perhaps even more in breadth. The bark is deeply textured and beautiful. The leaves are usually 2-4" long, rather flat, with deep to shallow, rounded lobes. They are deep green above, paler beneath, and take on pale to golden hues in fall, when the long, tapered acorns begin to drop. This should be a focal point of a large garden or commercial landscape, never cramped or restrained.
wislizenii. Interior live oak. I have already described most of this tree's prominent features under Q. agrifolia, above. It is similar overall, though with usually somewhat flatter, more obviously pointed leaves which often lack marginal teeth or spines. It has all the uses of Q. agrifolia and possibly (this is not proven, to my knowledge) even greater tolerance of drought.