Saguaro Cactus (Carnegiea gigantea). Sonoran Desert Arizona, USA. Record height: 78 feet - Average mature height: 18 to 30 feet but often reach heights of 50 to 60 feet - Weigh about 80 pounds per foot - Grow their first arms at around 12 feet in height or forty to eighty years of age but some never grow arms - Maximum age around 200 years. Protected from illegal collecting - Can produce around forty million seeds in a lifetime of which one may mature - Produce a cristate form which may be a genetic variant and occurs in about one in two hundred thousand individuals.