Ocotillo, a drought deciduous species

Last week we looked at how auxin production can influence leaf abscission in Coleus. Here in Minnesota, most deciduous tree species drop their leaves in the fall, when temperatures are getting lower and the days are getting shorter. But in arid regions, many plants are drought deciduous. Below is an excerpt from an earlier Field Notes blog post, taking a look at one such species that I encountered in Big Bend National Park.

Ocotillo (Fouquieria splendens) is another well-adapted desert plant very common in the Chihuahuan Desert. Most of its life is spent as a rather dead looking, spiny, leafless stalk (left) that can reach heights of 30 feet (more commonly 10-15 ft). But look closely and you’ll see green stripes along the stalk — these are active photosynthetic areas, allowing the plant to continue to produce sugars while leafless. Leaves (center) are produced quickly in response to rain, and are kept until drought conditions return, when these water-costly structures are dropped and the plant returns to its spiny, barren state. Brilliant orange-red tubular flowers (right) are produced at the tips of the stems sporadically throughout the year, with pollination service provided by hummingbirds and honeybees.