By Constance Casey
From the February issue of LAM:
“I could ask for no better monument over my grave than a good mesquite tree, its roots down deep like those of people who belong to the soil, its hardy branches, leaves, and fruit holding memories of the soil.”
This was the wish of the late J. Frank Dobie, beloved author of many books on Texas history, including Cow People and The Longhorns.
Many cow people, with their own deep roots in Texas, find mesquite far too rugged and tenacious—in fact, they consider mesquite a menace. The shrubby tree flourishes in some 60 million Texan acres, across the whole state except the eastern piney woods. Mesquite thrives in disturbed soil, and nothing disturbs soil like grazing cattle. Aggravate the native grass and mesquite is the opportunist that moves in. It is undiscouraged by drought or flood, adjusts to baking heat or freezing cold, and does fine in nutrient-poor soil, having the useful talent of its family, the Leguminosae (now known as Fabaceae), of nitrogen fixing.
Ranchers and farmers have tried for decades to wipe out mesquite; desperate measures include controlled burns, herbicides mixed with diesel fuel, and bulldozers dragging chains. The mesquite keeps coming back; it’s an indomitable natural force versus people, Texans, who like to think of themselves as indomitable. Mesquite can be literally wounding—its two-inch thorns are hostile to horses, cows, and cowhands. (There is a mesquite cultivar, ‘Maverick,’ that, despite being named for an unbranded calf or an independent, hard-to-control person, is thornless.)
“We had a little bit of a debate on the trees,” the Austin landscape architect Christine Ten Eyck, FASLA, recalls, using a tone that suggested understatement. The trees in question are honey mesquite (Prosopis glandulosa), and the project that inspired the debate is the courtyard of the Belo Center for New Media at the University of Texas. Ten Eyck was determined to use all native trees and plants, in part as a tribute to Lady Bird Johnson, a famed champion of wildflowers, who received her bachelor’s degree from the 1934 version of the journalism school. (That journalism career was thrown off track when she met Lyndon Johnson, then a congressional aide, on a trip to Washington, D.C.) Ten Eyck uses mesquite a lot in the desert projects that are her specialty, because, she says, “these trees survive where other trees don’t.”
In Ten Eyck’s creation, two rows of eight mesquite trees each form an allée, suggesting the formality of a European baroque garden. It’s a nice paradox: In essence she’s taken the mustang of trees and made it perform dressage.
For the media center students who sit in the courtyard, the mesquites will function as green umbrellas. In much of rural Texas, mesquites provide the only shelter from the sun. Other low-water-use trees such as ironwood and paloverde don’t provide as much shade. They’re wild and tough, but mesquite trees are also very pretty. They have mimosa-like feathery foliage and fragrant creamy flowers spring to autumn that are good for bees (thus mesquite honey).
Tamed or wild, mesquite has a loyal defender in Ten Eyck. “I get mad about people cutting down mesquites, when it’s really the ranchers’ fault,” she says. There’s more to the problem than overgrazing. The reduction of prairie fires that used to regenerate grassland has opened land to mesquite. There’s also an animal control problem—too much control. At the beginning of the 20th century there were hundreds of millions of prairie dogs nibbling away at mesquite beans, pods, and shoots, inhibiting the plant’s spread. (The pods and beans are also food for quail, jackrabbits, and deer.) Farmers and ranchers, with the support of the U.S. Department of Agriculture, perceived prairie dog colonies as a danger to livestock and competition for grass, and routinely poisoned them.
Honey mesquite is the most widespread of the seven or so species in Texas. There are more than 40 species worldwide, growing in arid and semiarid conditions. Many desert plants have shallow roots that sit just under the surface to suck up rain as soon as it falls. Mesquite, like creosote, has a different strategy. It sends down a root to tap into underground water, sometimes as far as 60 feet.
Mesquite as a city plant is not without problems. Chris A. Martin, senior sustainability scientist at Arizona State University, calls mesquite “shrubs on steroids.” If the crown is being lifted to make the green parasol, the trees will demand a lot of maintenance, he says—“you’ll be limbing up for years and years.” He recently coauthored a paper on how urban mesquite—overwatered and overpruned—is susceptible to bacterial infections. He advises homeowners going native to water any mesquite they plant sparingly. That’s hard, he says, because “that’s counterintuitive for Americans. They don’t want to wait. They want a nice, big tree right now.”
Even if you don’t overwater, your mesquite is likely, he says, to go seeking water in your neighbor’s yard. Ten Eyck disagrees. She says she has never seen mesquite, either by stolon or seed, invading a neighboring plot.
The name mesquite comes from the Mexican Spanish mezquite, which comes from a word in Nahuatl, an Aztec language, mizquitl. Of course, long before there were grazing longhorns or a Texas or an Arizona, mesquite was almost as important as corn for the indigenous peoples of the Southwest. They made flour from the sweet fleshy pulp around the seeds in the pod and tools from the extremely hard wood. Long before the wood became the gourmet choice for grilling fish and meat, Native Americans were using mesquite chips.
Martin says he’d be hesitant to plant mesquite in a plaza because of the litter production—“the pods make an intense mess.”
No problem, says Ten Eyck, remembering the Native Americans. “We can sweep them up and make cookies.”