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Range Habitat FlowersSonoran Desert of

southern Arizona

and northern Mexico

Desert slopes andflats

Blossom

The magnificent Saguaro Cactus, the state flowerof Arizona, is composed of a tall, thick, fluted,columnar stem, 18 to 24 inches in diameter, oftenwith several large branches (arms) curving upwardin the most distinctive conformation of all

Southwestern cacti.

The skin is smooth and waxy, the trunk and stems havestout, 2-inch spines clustered on their ribs. When water isabsorbed , the outer pulp of the Saguaro can expand like anaccordion, increasing the diameter of the stem and, in this way,can increase its weight by up to a ton.

The Saguaro often begins life in the shelter of a "nurse"tree or shrub which can provide a shaded, moister habitat for thegermination of life. The Saguaro grows very slowly --perhaps an inch a year -- but to a great height, 15 to50 feet. The largest plants, with more than 5 arms,are estimated to be 200 years old. An average oldSaguaro would have 5 arms and be about 30 feet tall.

The Saguaro has a surprisingly shallow root system ,considering its great height and weight. It is supported by a tap

root that is only a pad about 3 feet long, as well as numerousstout roots no deeper than a foot, emanating radially from itsbase. More smaller roots run radially to a distance equal to theheight of the Saguaro. These roots wrap about rocks providingadequate anchorage from winds across the rocky bajadas.

 

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Cactus Wren

The slow growth and great capacity of the Saguaro tostore water allow it to flower every year, regardless of rainfall.The night-blooming flowers, about 3 inches wide, have manycreamy-white petals around a tube about 4 inches long. Like

most cactus, the buds appear on the southeastern exposure of stem tips, and flowers may completely encircle stems in a goodyear.

A dense group of yellow stamens forms acircle at the top of the tube; the Saguaro hasmore stamens per flower than any other desertcactus. A sweet nectar accumulates in thebottom of this tube. The Saguaro can only be

fertilized by cross-pollination -- pollen from a different cactus.

The sweet nectar, together with the color of the flower, attractsbirds, bats and insects, which in acquiring the nectar, pollinatethe Saguaro flower.

Unlike the Queen of the Night cactus, not all of the flowerson a single Saguaro bloom at the same time.Instead, over a period of a month or more, only afew of the up to 200 flowers open each night,secreting nectar into their tubes, and awaiting

pollination. These flowers close about noon thefollowing day, never to open again. If fertilization has occurred, fruit will begin toform immediately.

 

The saguaro cactus isfound in this part of

Arizona.