The Saguaro: Ancestor, Calendar, Monument

The saguaro does not look like it should be alive. It stands on a hillside of bare rock and thin soil, in an environment that receives less than twelve inches of rain a year, in temperatures that swing from a hundred and fifteen degrees to freezing across a single calendar year. It does not look like something that should weigh six tons. It does not look like something that should live two hundred years. But it does all of these things.

The biology of the saguaro is a series of engineering solutions to impossible problems. Its roots spread outward rather than downward, a shallow radial system extending as far as the plant is tall in every direction, ready to collect every drop of a desert rainstorm the moment it hits the soil. The pleated trunk expands like an accordion as the plant absorbs water, storing hundreds of gallons after a good rain. The waxy outer skin seals moisture in and sun out.

The plant's timeline is almost incomprehensible in human terms. A saguaro seed germinates and grows perhaps six inches in ten years, sheltered beneath a nurse tree, a palo verde or mesquite that protects the seedling from frost and sun. The first flower appears after roughly forty years. The first arm does not appear until the cactus is between fifty and one hundred years old. A fully developed saguaro with multiple arms is a century-old organism at minimum.

The largest specimens in Saguaro National Park east of Tucson are estimated to be two hundred years old, meaning they were already mature when Mexican independence transferred this territory from Spain, already old when the Gadsden Purchase made it American, already ancient when the national monument was established in their honor in nineteen thirty-three.

For the Tohono O'odham, who have lived beside these plants for as long as anyone knows, the saguaro is not scenery. It is kin.