At first glance, the Tucson landscape may seem like a barren wasteland. But a closer look reveals a multitude of plant varieties. Most plants have protective adaptations necessary to survive the Arizona heat. Few plants are actively growing in the heat of June and July, but when August rains come, the desert comes back to life. Flowers also bloom during the cooler seasons of winter and spring.
Almost all trees in Tucson belong to the legume family and produce pods. The velvet mesquite produces long, edible pods and long, fern-like leaves. Its bark is dark brown to gray. Palo verde is easily recognized by its yellowish green bark and craggy appearance. In addition to pods, it produces yellow flowers. The acacia tree has small, greenish pods and light green to yellow flowers. Recognize ironwood by its fissured brown bark and brown-tipped spines. The ironwood tree has beautiful blooms that resemble sweet pea blossoms and brown, hairy pods.
Most people probably think of cactus when they think of spined, desert plants, but many other Tucson plants have spines as well. All of the trees mentioned previously have spines. The ocotillo produces long spikes of branches that grow vertically from the crown of the plant. The branches are covered with tiny leaves and sharp spines. The yucca doesn't have spines, but its thick, spear-like leaves leave a painful impression. The most common cactus in the Tucson desert include the barrel cactus, hedgehog cactus, cholla and saguaro. The barrel cactus is a thick, singular-stemmed plant that produces blooms on the top of the plant. Hedgehog cacti are tiny and rounded. Cholla produces many thin branches that form at right angles. Prickly pear (sometimes known as paddle cactus) produces thick, round pads. The saguaro is the queen of the desert. This long-lived but slow-growing plant grows to 75 feet high.
The native Tohono O'odham people are masters at using what the desert provides. Many desert plants serve practical purposes. The cockroach plant produces a poison that serves as an insecticide for many pests. Desert broom contains caffeine and ephedrine and produces a bitter tea consumed by Mormon pioneers. The sap from brittlebush is smoked as incense or chewed as a gum. The leaves of the agave tree are used as food, drinks, soap, fiber, and for medicinal purposes, while the coarse, fibrous yucca leaves are dried and used to make baskets, mats and shoes.
Many of the plants native to Tucson are found nowhere else on the planet, making a first visit seem otherworldly. However, a few plants, especially wildflowers, are familiar. August rains bring many wildflowers to life, especially on the highway from Wilcox to Tucson. Lupines, desert marigolds and penstemon all greet the weary traveler. The Arizona sycamore, one of the few Tucson trees with simple, deciduous leaves, lines the stream that meanders through Sabino Canyon.
Most cactus produce large, sometimes edible, fruits in late summer or fall. The fruits of the yucca are tubular and banana-like. Coral bell produces white fuzzy balls and poisonous seeds that are sometimes used in jewelry making.