We're constantly amazed at the variety of armament distributed among the plants of the Chihuahuan Desert: everything from the sharp, tough tips of yucca leaves to the jagged leaf edges of agaves and sotols to the great variety of cactus spines. Sometimes we're so awed by this array that we forget that there are forces of evil—from the plants' viewpoint, of course—undeterred by such weapons. Such as some insect predators that are just too small to be intimidated by large, clumsy defenses. More threatening, however, are the same kinds of organisms that threaten humankind: disease-causing fungi and bacteria.
We can all too well imagine the struggle between herbivores and thorny
defenses, but the other war is carried out at a level seldom recognized by us gigantic
humans until the battle is well underway--and frequently already lost. Leaves
disfigured by splotches of brown, tender growth wilting despite an abundance of water,
oozing ulcers on the stems of cacti or even the trunks of trees, these are the signs of
silent warfare. Signs that, too often, are harbingers of death.
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.