The last light of an Arizona desert sunset silhouettes the Saguaro cactus (Carnegiea gigantea) growing along a distant ridge. The Saguaro cactus can grow 50-feet-tall, is composed of 85% water, and can weigh over 8 tons. They are the largest member of the cactus family in the United States. Their skin is smooth and waxy with stout, 2-inch spines clustered on their ribs. The outer pulp can expand like an accordion when water is absorbed, increasing the diameter of the stem and raising its weight by up to a ton.
The Saguaro generally takes 47 to 67 years to attain a height of 6 feet, and can live for 150 – 200 years. During that lifetime, a single cactus will produce 40 million seeds; however, in its harsh native environment, only one of these seeds will survive to replace the parent plant. Indeed, young Saguaro’s must start life under a tree or shrub to prevent them from desiccating.