Parkinsonia microphylla (Yellow Palo Verde or Foothill Palo Verde) is a rare species in the Fabaceae (Legume) family that is native to the southwestern United States (southeastern California, southern Arizona) and northwestern Mexico (Sinaloa, Sonora, Baja California). The Palo Verdes were previously classified in the genus Cercidium, and some sources may still refer to it by that name. It is a bristling, upright-branching tree, mostly found on rocky slopes. It has a very restricted range compared with other species in this genus, and it is included on CNPS list 4.3. The species is slow-growing, sometimes living for several hundred years. It typically grows to heights of around 5 meter, although rarely it can reach 6-7 meter tall. Like others in the genus it has chlorophyll in the bark which allows photosynthesis to continue when the tree is leafless. It also has spines on the newer, slender stems. The leaves are yellowish green, very tiny, and during extensively dry and hot periods the tree will shed them. The flower is yellow or cream colored and typical of the genus. The fruit is a typical Legume seed pod. Like other Palo Verdes, it is an important tree for wildlife.