Small Leaf Horse Bean TreeThe Small-leaf Horse Bean (Parkinsonia microphylla, Torr.) has its leaf stems as well as leaflets much reduced. It grows in complexly gnarled form in the deserts of Arizona and California.
The yellow flowers are much smaller than those of the preceding species; the few-seeded beaked pods, larger. This little tree or shrub has its branches sharpened into stout thorns, which have green bark.