Up in the Deem Hills, and all over the Sonoran Desert, there are three dominant little shrubs, Brittlebush, Bursage, and Creosote. Each of them has to find a way to make a living in the hot, dry desert, where rain may be as little as 2 inches per year, and the air can heat up to over 120 F. By September, you would think any of these shrubs would just shrivel up and blow away. And they often do look like they are about to do just that!
The first little shrub, Bursage (Ambrosia deltoidea), the smallest and least widespread of the three, grows naturally in southern Arizona and northern Mexico. Bursage stays green year round, and has small, triangle-shaped leaves with soft hairs that reflect sunlight and help hold in moisture. When things get really hot, Bursage drops its leaves, and re-grows them after late summer and winter rains. Every summer, the sun beats down and says, “I’ll blaze and I’ll blaze, and I’ll dry you right up!” But Bursage keeps right on growing and flowering, and spreading seeds over the land. The second little shrub, Brittlebush (Encelia farinosa), is a bit larger and more widespread shrub, growing out into the Mojave Desert of California. Like its cousin, Bursage, Brittlebush leaves are covered with soft white hairs that reflect sunlight and help hold in moisture, and when things get really hot, Brittlebush drops its leaves, and re-grows them after late summer and winter rains. But while Bursage just has simple green flowers, Brittlebush lights up the desert with beautiful yellow sunflowers each spring so that the hills appear to be covered in gold. Every summer, the sun beats down and says, “I’ll blaze and I’ll blaze, and I’ll dry you right up!” But Brittlebush keeps right on growing and flowering, and spreading seeds over the land. The third and toughest little shrub, Creosote (Larrea tridentata), is the largest of the shrubs and grows throughout much of the desert southwest up into Nevada, west into California, east to Texas, and way down into Mexico. Creosote covers its leaves with a thin glaze that helps hold in water, and the tiny leaves can fold in half to further reduce water loss. Creosote sends down both deep taproots and spreads out long shallow roots, to absorb every last drop of water. After a good rain, the desert air is filled with the sweet smell of Creosote, and the shrub puts out a new crop of little yellow flowers. Every summer, the sun beats down and says, “I’ll blaze and I’ll blaze, and I’ll dry you right up!” But the Creosote keeps right on growing and flowering, and spreading seeds over the land. In Stetson Hills, the people loved the three tough and beautiful little shrubs so much, that they chose them to decorate their greenbelts, parks, and roadways. As in the Deem Hills above, Brittlebush, Bursage, and Creosote continue to live where they always have, down here on the flats before all of the people’s houses were built. Thus, the three little shrubs go right on growing through the blazing hot summers, flowering, and covering the landscape with seedlings, even if the irrigation system dries right up!
Since May 2005, I have written a natural history column for a neighborhood newsletter published by Jennifer Moore called "Our Big Backyard: Natural History of the Deem Hills," and since 2010, "A Suburban Naturalist."All of these columns are reproduced here. Deem Hills is a City of Phoenix Desert Preserve located just north of Happy Valley Road in north central Phoenix, and just west of I-17. The Preserve and adjacent hills comprise over 900 acres of open space with several miles of hiking trails. For more perspectives from the Deem Hills and suburban Phoenix, also check out my companion blog, Kat Tracks.
As a naturalist with a special interest in botany and plant ecology, some of my greatest passions are to explore, photograph and write about native plants. If I can spark an awareness or interest in natural history in others along the way, that is my greatest reward.