The Saguaro Above Tucson

The saguaro stands on a rocky slope of the Catalina Mountains above Tucson, its trunk and both arms cast from the same pleated green column. The arms branch from the trunk at the height of a man's shoulders, each having first pushed straight out sideways and then turned upward to grow as a second trunk of its own. The two arms are not twins: the right one is longer, rising past the crown of the main column, while the left is shorter and thicker, bent slightly as if it had taken a different angle toward the sun on its way up.

The skin that covers the whole plant is a waxy cuticle stretched over vertical pleats running from the soil to the top of the taller arm. The pleats are the plant's own instrument of weather. In a dry spring they fold sharp and deep, and the column looks fluted; after the summer rains they spread apart as the water-storing inner flesh swells, until the wall of the trunk turns almost smooth. The green is darkest inside the shadows of the pleats and palest along their ridges.

At close range, every ridge carries a row of small pale areoles, and from each areole grows a cluster of spines — one long, straight, pale center spine with a dark base, and shorter, slightly hooked ones around it. The spines are the whole defense of a plant with no bark. On the downhill side of the trunk they are brown and dull; on the uphill side they are amber and sharp.

Each arm continues the rib-line of the trunk, the pleats of the main column running up into the arm without a break, as if the arm were folded out of the trunk's own material rather than grafted onto it. Hidden inside all that green flesh is a skeleton of slender woody ribs running the full length of the plant, braced crosswise against one another. When the flesh finally rots away, what remains standing is a white cage of vertical ribs, light and open, the exact shape of the living plant; it falls to pieces a handful at a time until the curved ribs lie on the rock.

Gila woodpeckers work round nesting holes into a trunk this size, cutting at the flesh until it gives; the plant answers by clotting the wound with woody callus, sealing a dry cavity and leaving a healed ring darker than the rest of the skin. In late spring a crown of fuzzy buds rises at the tip of the main trunk and at the tip of each arm, opening at night into waxy white blossoms the breadth of a hand, and closing again before the heat of the day. By midsummer, where each blossom set, green fruit splits open to show red pulp crowded with black seed.

Below, the roots ignore the steepness. They run shallow, just under the surface of the slope, spreading outward in every direction as far as the arms reach, so that a rain touches them at the moment it begins its run to the arroyo. The whole plant leans out of plumb toward the downhill drainage, and the lower arm rides close above the rock at its base.

Photos: WClarke (CC BY-SA 3.0)