Trees do not clear themselves of branches on their lower trunks very early in life, and lumber more or less knotty results. It is possible, however, to cut a fairly large proportion of clear boards. The wood is of about the same weight as white oak, and is hard, strong, and tough. Its color is light brown, and the thin sapwood is hardly distinguishable from the heart. The medullary rays are as large as those of white oak, but are few. For that reason, swamp white oak does not give very satisfactory results when quarter-sawed. The bright patches are too scarce. Neither does it show as many of these rays as chestnut oak. The wood is very porous, but the large pores are confined to the springwood, while the broad bands of summerwood are dense. The contrast between the two parts of annual rings forms a strong, but not particularly handsome figure when the lumber is sawed tangentially--that is, from the side of the log. The wood finisher can improve this oak’s natural appearance by employing fillers and stains to lighten shades or deepen tints. The uses of this oak are numerous. It is excellent fuel, and is rather low in ash; it is weaker and more brittle than white oak; but it is quite satisfactory for railroad ties, car building, house finish, furniture, some parts of heavy vehicles, certain kinds of cooperage, and for farm implements. ROCKY MOUNTAIN BLUE OAK (_Quercus oblongifolia_) is named from the blue color of its foliage, though what little lumber is cut from it, is bought and sold as white oak. It is of little importance, yet in the almost timberless mountains of western Texas it supplies some of the urgent wants of a scattered population. It bears willow-like leaves one or two inches long, and less than an inch wide; but on vigorous shoots they are larger. The acorns are very small. Trees seldom exceed thirty feet in height, and a diameter of twenty inches; and often the trunk is divided near the ground in three or four stout, crooked forks. Ordinarily, it is an impossible tree to lumber, but sometimes a few logs find their way to sawmills and a little passable lumber is produced. The wood weighs 58 pounds per cubic foot. It is strong, but when it breaks, it snaps short. The heartwood is darker than in most oaks, and the sapwood is brown. The tree is useful for fuel. Charcoal for local blacksmith shops is manufactured from the wood. It is abundant on many of the sterile slopes and mesas of New Mexico and Arizona, but usually in the form of brush about the heads of canyons. [Illustration] COW OAK [Illustration: COW OAK] COW OAK (_Quercus Michauxii_)