And now we come to the beautiful Palo Verde (Parkinsonia) trees. Parkinsonia includes a number of different species and at least one important hybrid. They are among the most lovely of the native Sonoran desert trees, small and graceful, with a spectacular spring display of vivid yellow flowers.
In the wild they can sometimes be seen forming large roadside thickets; additionally they are currently one of the trees of choice for town planting. This use has been made even more desirable by the development of the widely-sold hybrid "Desert Museum". Said (The New Western Garden Book, see bibliography) to result from a combination of P. aculeata, P. microphyllum, and P. floridum, this variety has the advantage of being thornless (unlike P. aculeata), large-flowered, and cleanly, since it produces little litter from seedpods.
The different varieties are generally small (20 to 35 ft tall); some are faster growing than others. "Desert Museum" and P. floridum are said to grow quickly; P. microphyllum is a slow grower. The common name derives from the green bark color, which gives a pleasant hue even when the tree is out of leaf. The leaves themselves are tiny; they and the many twigs provide only filtered shade.
Happy with lots of sunlight and scanty water, these are classic plants for the desert garden.