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Desert Diary


Fruits come in an almost limitless variety. Even within one group of plants, the variations on a theme may seem endless. The bean family is a huge group which we generally can recognize by its fruit, what the botanists call legumes and what laypeople call bean pods. Most of us know that each kind of bean has differently shaped pods, and with a little thought, we also admit that the pea, despite not being called a bean, really belongs in that group.

One of the strangest pods, though, is one that is widespread in the Chihuahuan Desert. If you know Spanish, one of the common names—Tornillo—is a giveaway. For those of you who don't know Spanish, tornillo mean screw, and an English name for the plant is Screwbean Mesquite. The pod of this desert plant twists into a tight coil, looking much like an elongated screw or a tightly coiled, long spring. Despite its weird look, the beans can be ground into a meal for pinole bread or the pods boiled down into a sweet syrup.
pen and ink


Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.

screwbean mesquite fruits

Pods of Tornillo, or Screwbean Mesquite Prosopis pubescens. Photograph by Wynn Anderson.



Powell, A. M. 1998. Trees and shrubs of the Trans-Pecos and adjacent areas. University of Texas Press, Austin. 498 pp.

Vines, R. A. 1960. Trees, shrubs and woody vines of the Southwest. University of Texas Press, Austin. 1104 pp.

Web Resources

Summary with good pictures, distribution map.