This episode of Nature Notes was previously aired on March 11, 2011, and was written by Gary Nored.
One of the most interesting plants in the desert is the ocotillo. We love its odd growth habit and beautiful red flowers in the spring, so much so that it’s become a common landscaping pant throughout the southwest. But few people really know what it is. Though covered with large, sharp spines, it’s not a cactus. It grows up to thirty feet high, but it’s not a tree. So what is it?
Ocotillo, or Fouquieria splendens, is the only member of its family living in our area. The entire ocotillo is made of stems, which are completely covered with formidable spines that entirely protect it from livestock. Ocotillo blooms in the spring even in dry years, creating one of our area’s most brilliant wildflower shows.
When the plant is growing, the first leaves grow on an oversized leaf stalk and midrib. When these first leaves die, the leaf stalk and part of the midrib remain behind, hardening into the sharp, stiff and persistent spine that forms the plant’s primary defense against browsing animals. After the spines are established, tiny buds appear in the space between the stem and the spine. A completely different type of leaf grows from these buds. These leaves have very short stalks, are around two inches long, are rather soft, and grow in clusters of two to twelve. Ocotillo may grow new leaves seven or eight times a year, a remarkable accomplishment.
More amazing still is the fact that even rootless segments of ocotillo stems produce leaves when watered, and may do so repeatedly. The repeated ability of rootless ocotillo stems to produce new leaves without receiving nutrients or hormones appears to be unprecedented.
Ocotillo is an important food source for hummingbirds during their annual migration northwards from Mexico to the mountains of the western United States. Hummingbirds are the plant’s primary pollinator, though carpenter bees are also important. This is surprising, because carpenter bees cannot reach the inside of the blossoms, but obtain nectar by boring into the base of the flower from the outside. Nevertheless, crawling around and over many blossoms seems to do the trick.
And Verdins, small native birds, also appear to contribute to the plant’s pollination. Ocotillo has always been considered a useful as well as beautiful plant. Native tribes all over the southwest used the stems and fibers to build a variety of domestic structures. The Pima Indians manufactured some of North America’s earliest furniture out of ocotillo stems, de-thorned and bound together with rawhide strips. And Pima used ocotillo decoratively in their gardens as well, making them the first documented peoples to use native plants in landscaping.
Many building practices using ocotillo continue today. Every year, countless spring and summer visitors to Big Bend National Park take refuge in the shade of the ocotillo remada, that runs the length of the Castolon store. Visitors to the Barton Warnock Center gardens in Lajitas can enjoy the Palo Verde trees blooming, without having to see the parking lot behind them, thanks to a living fence.
Ocotillo should be starting to bloom right now. Look for them along roads or at lower elevations in the big bend state and national parks. And if we’re fortunate enough to get rains during the blooming season, you may get to see ocotillo with flowers and leaves. It’s a sight you won’t soon forget.