Feather bush (Lysiloma watsonii) is a gorgeous, soft-looking large shrub which can be pruned into a small tree. It is native to the Sonoran Desert, and is a great habitat and food tree for wildlife.
What gives the feather bush its name are the fine, soft green leaves; it is also known colloquially as desert fern and feather tree. The plant is from the legume family, and is related to the other famous legume in our desert — the mesquite. Its big advantage, however, is that it has no thorns, so it not only looks soft and delicate, it can be planted in areas where that look is important to your design. It is considered to be low-allergenic.
The flowers are little cream-colored puffballs which appear in spring and attract pollinators. The plant is essentially evergreen — it will drop its leaves in late winter but will replace them simultaneously, so it usually doesn’t look bare. The fact that it's a legume means it fixes nitrogen, turning nitrogen in the air into nutrients, so you shouldn’t fertilize it. It’s quite low-maintenance, particularly if you plant it in an area of the garden where the tiny leaves can stay under the tree and act as mulch. Note that it will have some seed drop as well, so if litter is a concern, plant it in a more naturalistic part of your yard.
It can be pruned gently in winter if you want it to have more of a tree shape. Most nurseries that sell it have already done this as it seems to be a more popular shape for this plant. It’s quite a slow grower, but eventually will reach a maximum of 15 feet in height. It likes full sun but will also grow in part shade. It prefers well-draining soil and is best for warmer areas of your yard as it may suffer some damage at temperatures lower than 28 F. It will need some supplemental water in our hot summers.
The branches and leaves offer nesting habitat for birds such as doves, cardinals, mockingbirds and quail. Feather bush is also a larval food for caterpillars of the large orange sulphur butterfly (Phoebis agarithe). The bark of the tree has been used medicinally for treating digestive problems.