FIG. 85.—A FOREST ON THE PLAINS OF SOUTHERN ARIZONA
Showing cholla and saguaro
Scattered among the huge club-shaped columns of the saguaro is the cholla, the next largest of the cactuses. This species, which is tree-like in its branching and in rare cases grows to a height of twelve feet, bears bright red or yellow flowers. One must approach with care, for its jointed stems are so easily broken that at the slightest touch of the hand or clothing, pieces break off and adhere firmly by means of their sharp curved and barbed spines. Another species of the cholla is small, reaching but a foot or two above the ground, but this and other low forms so cover the ground in places that one has to be constantly on guard to keep from running the spines into his feet.
These are not all the plants of this wonderful forest. The ocatilla is a cactus-like form having a group of long slender stems bunched together at the root. In the spring each is tipped with a spike of red flowers, and as the snake-like stalks wave in the breeze they present an appearance scarcely less attractive than the saguaro.
FIG. 86.—OCATILLA
Scattered among the vegetation just mentioned is the palo verde (green tree), so named from the yellowish green of its bark. It is remarkable for the small size of the leaves, which afford scarcely any shade for the traveller upon a hot summer day. (Fig. 84.)
Along the dry water courses we find the mesquite, a tree which does not grow upon the gravelly plains and rocky slopes, for it needs more moisture than most of the desert vegetation. In the spring it puts out delicate green leaves which form a pleasing contrast with the other plants.
Riding through one of these forests in the deepening twilight, one is impressed with a feeling of awe and mystery by the strange, weird shapes outlined against the sky. In the cooler air of evening the animals come from their retreats. The insects and the snakes are then abroad, and if one is on foot the sudden buzz of a rattlesnake is not a pleasant sound to hear.