Everything about the saguaro is a lesson in patience, and in place. It is the plant the whole country borrows to mean "desert," the giant with upraised arms on every Western postcard — and it grows wild almost nowhere on Earth but here, in the Sonoran Desert of southern Arizona, a sliver of California, and the Mexican state of Sonora. Step outside that narrow band and the saguaro cannot live; a hard freeze kills it. Inside it, the cactus is king.
It earns the title slowly. A saguaro grows about an inch a year, spends its first decades in the shade of a "nurse" tree — a palo verde, an ironwood, a mesquite — that shelters the seedling from sun and frost, and does not flower until it is around thirty-five years old. It may not raise its first arm until it is past fifty, and it can live two centuries, rising forty feet or more and weighing several tons when the summer rains fill its pleated trunk with water. Nothing about it is fast, and everything about it is load-bearing: the saguaro is a keystone species, holding up more than a hundred others. Gila woodpeckers and gilded flickers drill nest holes in its flesh; when they move out, elf owls and other tenants move in. Its white flowers open at night and are pollinated chiefly by the lesser long-nosed bat, which migrates up from Mexico to drink the nectar, while doves and bees take the day shift. The Tohono O'odham have gathered its red fruit to open their new year for longer than there has been a country to call this a state. Take away the saguaro and the desert loses its landlord.
That floor of cactus and creosote is only half the story, though — the low half. What makes the far southeast of Arizona one of the most surprising places in North America is what rises out of it. Scattered across the desert like ships at anchor are dozens of separate mountain ranges — some forty of them across southeastern Arizona, southern New Mexico, and northern Mexico — each climbing thousands of feet out of the desert sea into cool forest at the top. Biologists call them the sky islands, and the name is exact. A range like the Santa Catalinas above Tucson, or the Chiricahuas farther east, is an island of high, wet, forested habitat marooned in an ocean of dry desert, cut off from every other mountain by the hostile lowland between.
The consequence is that these mountains stack the whole continent into a few vertical miles. Climb one and you pass, in a single afternoon, through the same succession of climates you would cross driving from Mexico to Canada: Sonoran desert at the base, then grassland, then oak woodland, then tall pine, and finally, on the highest peaks, the spruce and fir and aspen of the Rockies. The drive up Mount Lemmon out of Tucson runs from the saguaros to the snow line in under an hour. And because each island is cut off, life on it drifts and specializes; the sky islands together hold something like seven thousand species of plants and animals, one of the richest concentrations on the continent. This is the one corner of the United States where the life of Mexico's Sierra Madre reaches its northern edge and the life of the Rocky Mountains reaches its southern one, and the two overlap. Jaguars have padded back across the border into these ranges; the elegant trogon, a bird of the Mexican highlands, nests in the canyons here and nowhere else in the country.
Nowhere is the effect more vivid, or more beautiful, than in the Chiricahua Mountains, the sky island at the far southeastern corner. Some twenty-seven million years ago a volcano called the Turkey Creek caldera erupted and laid down a thick sheet of rhyolite; wind, water, and ice have since carved that rock into a forest of stone — thousands of balanced pinnacles and columns standing shoulder to shoulder up the mountainsides. The Chiricahua Apache, whose homeland and fortress this was, called it the Land of the Standing-Up Rocks, and it is impossible to stand in it and think of a better name. This is Cochise's country and Geronimo's; the range gave the Apache both a stronghold and, in the end, the ground the Army fought them for. The rock forest is only the most photographed part of a mountain that is, all the way up, a ladder of climates.
Down on the desert floor between the ranges sits Tucson, and Tucson is proof that people have understood this landscape for a very long time. The city keeps its O'odham name, Cuk Ṣon — "at the base of the black hill" — and the ground beneath it has been farmed for more than four thousand years, some of the oldest continuously cultivated land in North America. The people who first planted here read the desert the way its plants and animals do: they worked the floodplain of the Santa Cruz, gathered the saguaro fruit, drew on the tepary bean and the mesquite and the cactus bud, and used the sky islands as a vertical pantry, following the seasons up and down the mountains. Modern Tucson, ringed by five of those ranges, became the first city in the United States that the United Nations named a City of Gastronomy — an honor rooted, in the end, in four thousand years of paying attention to what grows here.
That is the shape of the Sonoran South: a floor ruled by a slow giant that lives nowhere else, and above it a scatter of islands that each hold a whole continent's worth of life. It is the rare desert that gets richer the closer you look and the higher you climb — and it rewards, above all, the patience the saguaro has been modeling all along.