ROCKY MOUNTAIN OAK (_Quercus undulata_) bears acorns which may be eaten like chestnuts, and not much more may be said for the tree in the way of usefulness to man, though it is the salvation of some of the small mammals of the bleak Texas and New Mexico hills where there is little to eat and few places for concealment from hawks and other enemies. The tree is also called scrub oak and shin oak. It grows in Colorado, New Mexico, western Texas, Arizona, Nevada, and Utah. At its best it rarely exceeds thirty feet high and a foot in diameter, and it often forms a jungle of shrubs through which the traveler must wade waist deep or go miles out of his way to pass round it. Its leaf is one of the smallest of the oaks, and is notched much like the chestnut leaf. ALVORD OAK (_Quercus alvordiana_) is little known and will probably never be of much importance. It grows in the region of Tehachapi mountains, the northern border of the Mojave desert, in California, and was named for William Alvord of that state. The leaf is toothed, and the acorn smooth. No record has been found of any use of the wood, and when Sudworth compiled his book, “Forest Trees of the Pacific Slope,” he was unable to procure enough leaves, flowers, and fruit to enable him to give a botanical description. It may therefore be regarded as one of the scarcest oaks in the United States, which fact gives it a certain interest. SADLER OAK (_Quercus sadleriana_) is one of the minor oaks of the Pacific coast, and is popularly and properly called scrub oak by those who encounter it on high, dry slopes of northern California and southern Oregon mountains, from 4,000 to 9,000 feet above the sea. It forms dense thickets, and passes for an evergreen. Its leaves remain on the branches only thirteen months. The leaves are toothed like those of chestnut. The acorns are matured in one season. The name Sadler oak was given it in honor of a Scottish botanist. Trees are too scarce and too small to have much value, except as a ground cover. BREWER OAK (_Quercus breweri_) grows on the west slope of the Sierra Nevada mountains in California, from Kaweah river northward to Trinity mountains. It is often little more than a shrub, and its usefulness to man lies less in the quantity of wood it produces than in the protection the dense thickets, with their network of roots, afford steep hillsides. Gullying in time of heavy rain cannot take place where this oak’s matted masses of roots bind the soil. Sprouts rise freely from the roots, and thickets are reproduced in that way rather than from acorns, although in certain years crops of acorns are bountiful. The trunks are too small to make any kind of lumber, but are capable of supplying considerable quantities of fuel. [Illustration] POST OAK [Illustration: POST OAK] POST OAK