Ocotillo (Fouquieria splendens) is an unusual looking plant native to the Desert Southwest that has evolved an amazing adaptation to thrive in a hot arid environment.
1. It grows and drops its leaves with the rain - Ocotillo is drought deciduous. Its shallow roots are perfect for capturing rain from those rare desert storms, and it will begin growing leaves within 24 hours. Most of a plants water is lost through its leaves, so once it becomes dry again it will lose its leaves. It can cycle through this up to five times a year.
2. You can see how many growth spurts it has had by looking at its stems - Just like a tree makes rings when it goes dormant in the winter, you can see when an ocotillo goes dormant between rains. A line will divide each section of growth along the stem.
3. During drought it may not leaf or grow, but it will always flower - If times are so dry that there is a possibility it will die, it will forgo growing and allocate its precious stored water to flowering and producing seeds. That way a new generation of ocotillo will have the chance to germinate and produce new plants.
4. Ocotillo has several pollinators including hummingbirds - many of which time their migration to the blooming of ocotillo flowers.
pic DSC_3695-01 Ocotillo flowers, by J.J. https://flic.kr/p/csCDD CC BY-NC-ND 2.0
5. Carpenter bees are nectar robbers - Hummingbirds can reach the nectar at the bottom of the long flowers. In return for giving nectar, the flower will deposit a little pollen on its head so that it will pollinate other flowers. Carpenter bees can’t reach the nectar, so they cut a hole at the base of the flower, by-passing the pollen. Fortunately for the ocotillo flower, the bees' rear-end reaches the anther and deposits pollen on it.
Carpenter bee (Xylocopa) on ocotillo, by Gary Nored https://flic.kr/p/6QbyA6 CC BY-NC 2.0
Special thanks to Keith Killingbeck for lending his expertise and photos for this post.
By Johnny Ramirez
USDA ARS The Jornada Experimental Range
For more information:
Killingbeck, Keith T. (2008) Can zinc influence nutrient resorption? A test with the drought-deciduous desert shrub Fouquieria splendens (ocotillo). Plant Soil, 304:145-155.
Killingbeck, Keith T. (1996) Tracking environmental change with the desert shrub ocotilo (Fouquieria splendens): Prospects and pitfalls. Proceedings: shrubland ecosystem dynamics in a changing environment.
US Forest Service Index of Species Information - Fouquieria splendens: https://www.fs.fed.us/database/feis/plants/shrub/fouspl/all.html