Some good trees for southern Nevada
We may complain about some of the horticultural problems posed by the Mojave Desert, but life in the great American Southwest has a several advantages for gardeners. Low humidity means few plant diseases, bright sun makes many plants grow faster, and the temperatures permit us to grow vegetables and other plants virtually year round.
Those who arrived from parts of the country where autumn is a time of vivid foliar colors occasionally sigh wistfully about the lack of fall color we get. Deciduous trees lose all their leaves at once, sometimes after they have developed bright and different colors. Trees in our mountains are generally conifers, which do not have leaves that can change into a fabulous red, orange and maroon display for miles on end.
Pinyons, junipers, and bristlecone pines are evergreens, with the emphasis on green. Year round, the leaves remain more or less the same color. This does not mean they never lose their leaves. They simply drop them throughout the year. People with pines growing near their pools can be surprised to discover they are constantly scooping out needles to clean the pool.
"Conifer" comes from the Latin for "cone bearers;" this is how they produce their seeds. Not all evergreens create cones however, but rather reproduce by flowers and fruits. We call these "broadleaf evergreens." They remain leafed out for the whole year, but do not create a color show. Some of these grow well in our desert environment: shoestring (A. stenophylla) and mulga (A. aneura) acacias remain green, as do larger trees like olives (Olea europaea), African sumac (Rhus lancea), and even a few oaks (Quercus spp.)
Looking around at urban landscapes in Southern Nevada, we can see some reds and yellows, as increasing numbers of residents choose to grow trees particularly for their fall color. Following these brightly colored displays is a winter of leafless branches, but for some of us, an acceptable trade-off.
Several ash trees (Fraxinus spp.) provide good fall color, often in deep crimson or purple shades. The leaves of Raywood (F. angustifolia), Arizona (F. velutina), and Modesto (F. velutina 'Glabra') ashes are all bright in the autumn. Unfortunately, they may require more water than one can apply and still feel ecologically virtuous.
Chinese pistache is a cousin of pistachio. Its leaves turn lovely colors as days shorten and temperatures cool. While not exactly a desert plant, it does not need a large amount of irrigation to stay healthy.
This grouping is not exhaustive. It does not include any with spines or thorns. At the request of my family, I am currently trying to limit the amount of armament in my own landscape. I have also not included the many trees whose bark is interesting, especially in the winter when there is little else to catch the eye.
My message for this happy New Year is – consider installing things that remain bright green through the winter, and do not forget that you can have colorful fall foliage.
Dr. Angela O'Callaghan is the Social Horticulture Specialist for University of Nevada Cooperative Extension. Contact firstname.lastname@example.org or 702-257-5581.