Prosopis juliflora, DC.
The mesquite or honey pod is one of the wonderful plants of the arid and semi-arid regions from Colorado and Utah to Texas and southern California. At best it is a tree sixty feet high along the rivers of Arizona. In the higher and more desert stretches it is stunted to a sprawling shrub, with numerous stems but a few feet high. Its leaves are like those of our honey locust but very much smaller, and the tree furnishes little shade. The bark of the trunk is thick, dark reddish brown, shallowly fissured between scaly ridges. In winter the tree looks dead enough, but the young shoots clothed with tender green bring it to life in early spring, and the greenish fragrant flowers, thickly set in finger-like clusters, appear in successive crops from May to July. These are succeeded by pods four to nine inches long in drooping clusters, each containing ten to twenty beans.
Not its beauty of leaf and blossom but its usefulness is what makes this tree almost an object of worship to desert dwellers, red men and white. The long fat pods supply Mexicans and Indians with a nutritious food, green or ripe. Cattle feed upon the young shoots and thrive, when other forage is scant or utterly lacking. The fuel problem of the desert is solved by the mesquite in a way that is a great surprise to the newcomer. His sophisticated neighbor takes him on a wood-gathering expedition. Stopping where a shrubby mesquite sprawls, he hitches his team to a chain or rope that lays hold of the trunk, and hauls the plant out by its roots. And what roots the mesquite has developed in its search for water! There is a central tap root that goes down, down, sometimes sixty feet or more. Secondary roots branch out in all directions, interlock, thicken, and form a labyrinth of woody substance, in quantity and quality that makes the timber above ground a negligible quantity. This wood is cut into building and fencing materials—two great needs in the desert. The waste makes good fuel, and every scrap is precious. Posts, railroad ties, frames for the adobe houses, furniture, fellies of wheels, paving blocks, and charcoal are made of this wonderful tree's root system. A gum resembling gum-arabic exudes from the stems.
The Screw-bean
P. pubescens, Benth.
The screw-bean or screw-pod mesquite is a small slender-trunked tree with sharp spines at the bases of the hoary foliage. The marked distinction between this species and the preceding one is in the fruit, which makes from twelve to twenty turns as it matures, and forms when ripe a narrow straight spiral, one to two inches long; but when drawn out like a coiled spring the pod is shown to be more than a foot in length. These sweet nutritious pods are a most useful fodder for range cattle, and the wood is used for fencing and fuel. This tree grows from southern Utah and Nevada through New Mexico and Arizona into San Diego County, California, western Texas and northern Mexico.
The Palo Verde Acacia
Cercidium Torreyanum, Sarg.
The palo verde is another green-barked acacia whose leaves are almost obsolete. Miniature honey-locust leaves an inch long unfold, a few here and there in March and April, but they are gone before they fully mature, and the leaf function is carried on entirely by the vivid green branches. Clustered flowers, like little yellow roses, cover the branches in April, and the pointed pods ripen and fall in July.
In the Colorado desert of southern California, in the valley of the lower Gila River in Arizona, on the sides of low canyons and on desert sandhills into Mexico, this small tree, with its multitude of leafless, ascending branches, is one of the brightest features on a hopelessly dun-colored landscape.