The universal symbol of North American deserts is the cactus, visualized by most people as a mass of spines. Indeed, most desert plants seem to be well armed. To the botanist, though, not all pointed plant weapons are the same. A spine, for example, is kindred to a leaf, arising from deep within the stem and much like a hardened, pointed leaf rib without the flat blade. The spine is the chosen weapon of the cactus, and a fine weapon it is. Of course, if we stick to botanist-speak, we can no longer talk about their prickly nature.
Thorns are branches modified to attract the attention of the most
other-worldly soul. Our Chihuahuan Desert shrubs known as Javelina Bushes seem to be
practically nothing BUT thorns. Other sharp reminders are known as prickles, and are
outgrowths of the bark or outermost parts of the stem. Rose growers' attention
often is grabbed by these. Ask yourself when you're snagged by a bush. Is it by a
thorn, a prickle, or a spine? By whichever, you're sure to get the point!
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.