The Southwestern Walnut
Juglans rupestris, Engelm.
The walnut of the Southwest grows into a spreading, luxuriant tree, where its roots find water. But on the canyon sides, and higher on mountain slopes, it becomes a stunted shrub, because of lack of moisture.
The nut is smaller than that of the eastern walnuts and has a thick shell, but the kernel is sweet and keeps its rich flavor for a long time. The Mexicans and Indians are glad to have this nut added to the stores they gather for their winter food.
One striking feature of this tree is the pale, cottony down on its twigs, which sometimes persists three or four years. The long limbs droop at the extremities, almost deserving to be called "weeping." But nothing could be more cheerful in color than the yellow-green foliage, shining in the sun, against the white bark of the tree. In autumn the foliage turns bright yellow. A specimen, much admired, grows in the Arnold Arboretum in Boston.
The California Walnut
J. californica, Wats.
The California walnut is a stocky, round-headed tree, with heavy, drooping branches, and bark that is white and smooth on limbs and on trunks of young trees. Ultimately the trunk turns nearly black, and is checked into broad, irregular ridges. In bottom lands, along the courses of rivers, back thirty miles from the coast, these trees are found, from the Sacramento Valley to the southern slopes of the San Bernardino Mountains.
The foliage is bright pale green, feathery, the leaflets often curved to sickle form, showing paler silky linings. Californians admire and plant this tree for shade and ornament. Its greatest value is as a hardy stock upon which the "English" walnut is grafted by nurserymen, for planting orchards of this commercial nut. The fruit of the native nut is excellent, but it cannot compete with the thin-shelled nut that came from Persia, via England.
The Butternut, White Walnut, or Oilnut