Cactus Country

An Arizona canyon provides a taste of desert and a glimpse of uplands.

Rising above the Sonoran Desert, the Santa Rita Mountains extend north to south, falling roughly midway between Tucson, Arizona, and Nogales, Mexico. The highest peaks, including 9,453-foot Mount Wrightson, are topped off with verdant forests of Engelmann spruce and ponderosa pine, while cacti and other desert plants grow at the base of the mountains, at about 3,000 feet, and penetrate dry canyons up to 4,000 feet. The range is a favorite among naturalists because of its varied plant and animal life and the scattering of natural springs, but only a few routes provide easy access into the rugged terrain. The most popular destination, reached by a highway that pierces the north side of the region, is a camping and recreational facility at the head of Madera Canyon; my favorite locale, however, is Agua Caliente Canyon, best reached from the west. Both canyons are under the jurisdiction of the Nogales Ranger District of the Coronado National Forest.

Lying at 3,600 to 4,200 feet, Agua Caliente Canyon harbors mostly desert grassland and isolated stands of oak, while pinyon pine and alligator juniper are scattered on the surrounding dry, rocky slopes. Natural springs help feed some streams that flow intermittently in response to rainfall; other streambeds are washes, entirely dry except after heavy rains. One reason I am attracted to this canyon is that it is one of the few places in the United States where one can find two species of Amoreuxia, which are essentially tropical wildflowers. The birdlife, too, is alluring. Several species of hummingbirds flit about the blooms of the Arizona trumpet and the desert honeysuckle, while the rat-tat-tat of five different kinds of woodpeckers may be heard. Occasionally the elegant trogon, more common in Mexico, will fly overhead. Mammals are also plentiful. Although rarely seen, mountain lions and bobcats periodically cross the canyon. Likelier to be encountered are javelinas (collared peccaries) and coatimundis (large, ring-tailed cousins of the raccoon).

To get to Agua Caliente Canyon, exit Interstate 19 at Canoa Road and follow the east frontage road south before turning eastward into the canyon on Elephant Head Road. Eventually you will connect with a road that climbs along the south side of the canyon, heading toward the Smithsonian Institution's Fred Lawrence Whipple Observatory. Tours of that facility, located on the 8,585-foot summit of Mount Hopkins, depart from a visitors center and are available by reservation. Before you reach the visitors center, located at the base of Mount Hopkins, you will find a rough, unpaved road that leads off to the left for a quarter mile, down into the canyon, to Agua Caliente Spring. As its name indicates, the water from this spring is hot. Heated underground through geothermal processes, the water feeds an intermittent stream.

From the spring, you can pick up any of several hiking trails. One that heads toward Mount Hopkins passes two rocky knolls that top off at 4,962 feet and 6,012 feet. Together they are known as the Devils Cash Box, named for a 1909 gold strike. Intrepid hikers can also trek onward to the Madera Canyon campground or the summit of Mount Wrightson.

HABITATS

Desert grass:Land plants include many cacti, the most spectacular of which are the saguaro, with its thick, armlike branches, and a number of large chollas, such as the tree cholla, the jumping cholla, and the cane cholla. Also prominent are various prickly pears, with their fiat, padlike stems, and the fiercely spined Arizona barrel cactus, which may grow to a foot in diameter and more than three feet tall. Smaller species include the Arizona rainbow cactus, sporting multicolored spines; claret cup, named for its flower; pancake cactus, which grows up to four inches in diameter and lies flat on the ground; pincushion cactus, which stands about two inches tall; and the two- to five-inch-tall nipple cactus, whose stems end in small rounded tips.

A plant with cactuslike spines that is actually related to Mexico's boojum tree is ocotillo. After a rain, its barren, gray-black stems change overnight to green as small leaves emerge from buds covering the plant. After a few days of dry weather, the leaves fall off and the plant resumes its dormant appearance. While cactus flowers have many petals, the ocotillo's red flowers have only five, united at their base to form a tube.

Stands of oak may appear in shallow depressions and other places that have slightly more moisture. The dominant (and often only) species is Gambel's oak.

Dry, rocky slopes support a few kinds of stunted trees, among them Gambel's oak, silverleaf oak, pinyon pine, and alligator juniper. Most do not grow more than twenty feet tall under the arid conditions. Typical shrubs include squawbush (a type of sumac); coral bean and fairy duster (both members of the pea family); two types of hibiscus, or rose mallow; and cliff Fendler bush. Snapdragon vine, a plant with arrowhead-shaped leaves and dark red or bluish purple flowers with a yellow center, scrambles over some of the shrubs. Prickly pear cacti found here are the clock-face prickly pear, Engelmann's prickly pear, cliff prickly pear, and purple prickly pear. Wildflowers that grow scattered in rocky soil include pine-needle milkweed, Arizona trumpet, long-leaved phlox, and a true wild cotton. Two uncommon species with three-inch-wide orange flowers are Amoreuxia palmatifida (yellow show) and A. gonzalezii, the only two members of the tropical Cochlospermaceae family that are found in the United States.