The desert willow (Chilopsis linearis) takes its name from its form and from its leaves, but this tree is not a true willow. The desert willow grows to be a small tree or large shrub, producing orchid-like flowers throughout the summer that bees and hummingbirds visit. The desert willow is an ornamental species that the University of Arizona website notes often beautifies roadsides in the Southwest. The leaves of desert willow are easy to identify from their size, shape, color and other features.
The leaves of the desert willow can be as long as 5 inches. The width of the leaves, about 1/2 inch, giving them a similar appearance to the foliage of willows, such as the weeping willow and the sandbar willow. These two types, according to the "National Audubon Society Field Guide to Trees," have similar sized leaves.
The desert willow foliage, once it fully develops, takes on a pale green shade. The leaves provide a vivid background for the flowers, which emerge no later than the end of June. The flowers are white, with yellow and purple splashed about on their insides.
The Arid Zone Trees website reports that the leaves on a pruned desert willow allow enough light to filter down to the ground as not to prevent plants from growing beneath the tree. However, younger developing desert willows tend to have thick canopies of leaves, meaning a schedule of regular pruning is necessary to keep these specimens from appearing "shaggy."
In their natural setting, the desert willows grow along waterways in the Southwest and in washes in dry regions where any rainfall may tend to collect in the ground. These are deciduous trees, meaning that they shed their leaves in the winter. A desert willow normally begins to drop its foliage in late November. However, in times of extreme drought, the desert willow will shed leaves in an attempt to conserve water, with the leaves piling up beneath the tree.
Many people mistake the desert willow for a member of the willow family because of the shape of the leaves and the manner in which they hang down towards the ground, even though, unlike a weeping willow, the branches do not droop. However, the desert willow belongs to the Bigonia family, a group that includes the catalpas and many other plants of a tropical nature.