Native Trees

From mesquite to bristlecone, Arizona's famed diversity includes no less than 126 species of NATIVE TREES

"Look, Mom," I said, holding up a reference book, "the most remote tree in the world is 31 miles from any other tree." Mom squinted across the kitchen table, reluctant to use her glasses. She lived in a northern Kentucky community and had never traveled more than a hundred miles from it."Where is it?" she asked. "In Arizona?" Despite modern communications, mul-titudes still envision Arizona as a sunbaked Saharan sprawl. Just add cowboys, Indians, the Grand Canyon, Phoenix, Tucson, and cactus. More cactus than anything else.

Certainly we have our share of cactus and have become justifiably famous for the giant saguaro, which grows to 50 feet and 50 tons. But "cactus country" really only takes in about a third of the state. The continental United States can claim a minimum of 679 different native species of trees (including a few naturalized imports that now reproduce themselves in the wild). Arizona plays host to no less than 126 of these. Where specific tree species grow is determined by a number of factors. Among them are altitude, rainfall, and whether slopes face north or south. In Arizona, elevations range from 73 feet above sea level south of Yuma to 12,670 feet at the summit of the San Francisco Peaks near Flagstaff. This spread covers six of the western continent's seven life zones: Lower Sonoran, Upper Sonoran, Transition,

Canadian, Hudsonian, and Alpine. Even without the above-timberline climes of the Alpine zone, the rest accommodate a great diversity of tree types. In the Lower Sonoran Zone (below 4,500 feet), mesquite, ironwood, and paloverde (Arizona's official state tree) dominate; there also are native palms and elephant trees. Principal types of the Upper Sonoran (elevations of 4,500 to 6,500 feet) are juniper, piñon pine, and Gambel's oak. The Transition Zone (6,5008,000) harbors ponderosa pine and Douglas fir. Cover in the Canadian Zone (8,0009,500) is largely Engelmann and blue spruce, white and subalpine fir, and quaking aspen. In the Hudsonian (9,50011,500) grow Engelmann and blue spruce, subalpine and corkbark fir, and that ancient of ancients, the bristlecone pine. The borders of these life zones are not hard and fast, of course, and trees typical of one zone frequently reach into another. Less dominant and sometimes less recognizable to the layman, but still common, are the limber, Chihuahua, and Apache pines; Arizona cypress; narrowleaf and Fremont cottonwoods; and 11 kinds of willows, including desert, Pacific, and peachleaf. Arizona has a dozen species of oaks, a native black walnut, and a wild olive. We have maples and birches, elders and alders, ashes and acacias. You can find redbud and rosewood, kidneywood and dogwood, tamarisk and tree tobacco, sycamore, sumac, smokethorn-and a lot more. And that's not counting the introduced domesticated species. Mom has since journeyed across Arizona, highland and lowland, often amazed. There's no tree separated from its fellows by 31 miles here. The world's most remote tree, the one I once told her about, was in the Tenere Desert of the Niger Republic. It survived being rammed by a careless truck driver, was subsequently transplanted, and now lives in safety and honor in a museum at Niamey, Niger. Yes, people come to Arizona expecting to find desert. There's plenty of that, all right. But after you subtract the cactus country from the whole of Arizona, much of what's left is hard to see because of the trees.