Flora and Fauna News

Cassias Giving Splash of
Yellow to Urban Landscapes

By Michael Plagens
Sonoran Desert Sciences

Several species of xericly adapted Cassias are over-planted in the urban areas of Phoenix and Tucson. These have now begun blooming profusely adding yellow color to our roadsides and yards. These plants are very hardy having evolved in the Australian deserts, but would not be heavily blooming every year without some irrigation. They belong to the plant family Fabaceae which includes beans, mesquites, and palo verdes. And like palo verdes, they also belong to the subfamily Caesalpinioideae. On rare occassions a few bees, such as the large black Carpenter Bee and domestic Honey Bee will visit the flowers and also the caterpillars of the Cloudless Sulfur butterfly will be found eating the leaves. According to U. of Arizona extension employee Cheri Melton, these Australian Cassia species are toxic to the butterfly larvae causing them to die. In other words, these exotic plants do not contribute much to the Sonoran Desert ecology and should be avoided.

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Desert Cassia, Cassia nemophilla, a widely planted xeric landscape shrub native to Australia. Photo by Philippe Faucon. Please visit and bookmark the incredible collection of information gathered by Sula and Philippe on their web site Phoenix Tropical Gardens!

Cloudless Sulfur, Phoebis sennae.
Photo by Bruce Walsh. Butterflies of Southeastern Arizona