Native to southwestern U.S. and Mexico. Rapid growth at first, then slowing; eventually reaches 1530 feet high and wide. Yellow-green bark, spiny twigs, picturesque form. Sparse foliage; leaves 69 inches long, with many tiny leaflets that quickly fall in drought or cold. Numerous yellow flowers in loose, 3- to 7 inches-long clusters. Blooms over a long season in spring, inter- mittently throughout the rest of the year. Flowers are followed by 2- to 6 inches-long seedpods that mature in summer.
A good choice for water-conserving gardens, since it grows in dry soil; also performs well in moist soil as long as drainage is good. Tolerates alkaline soil. Requires minimal care once established. Stake young trees, and train for high or low branching. As a shade tree, it filters sun rather than blocking it. Thorns and sparse foliage rule it out for tailored gardens, and litter drop can be a problem. Flowering branches are attractive in arrangements. Hardy to 18F.