MEXICAN PINON (_Pinus cembroides_) is known also as nut pine, pinon pine and stone-seed Mexican pinon. It is one of the smallest of the native pines of this country. The tree is fifteen or twenty feet high and a few inches in diameter, but in sheltered canyons in Arizona it sometimes attains a height of fifty or sixty feet with a corresponding diameter. It reaches its best development in northern Mexico and what is found of it in the United States is the species’ extreme northern extension, in Arizona and New Mexico at altitudes usually above 6,000 feet. It supplies fuel in districts where firewood is otherwise scarce, and it has a small place as ranch timber. The wood is heavy, of slow growth, the summerwood thin and dense. The resin passages are few and small; color, light, clear yellow, the sapwood nearly white. If the tree stood in regions well-forested with commercial species, it would possess little or no value; but where wood is scarce, it has considerable value. The hardshell nuts resemble those of the gray pine, but are considered more valuable for food. They are not of much importance in the United States, but in Mexico where the trees are more abundant and the population denser, the nuts are bought and sold in large quantities. Its leaves are in clusters of three, sometimes two. They are one inch or more in length, and fall the third and fourth years. Cones are seldom over two inches in length. The species is not extending its range, but seems to be holding the ground it already has. It bears abundance of seeds, but not one in ten thousand germinates and becomes a mature tree. [Illustration] WHITEBARK PINE [Illustration: WHITEBARK PINE] WHITEBARK PINE (_Pinus Albicaulis_)