The park was named after the Sagauro cactus. They are very tall and have "arms" that grow straight up unless they have been bent from the weight of snow when they were young. This can produce very strange shapes. Saguaro National Park is part of the Sonora desert and yes it does snow and get very cold here. The Saguaro is called the monarch of the Sonora desert and has been protected in the park since 1933. These are the largest cacti in the United States. They can live to 200 years and reach 25 feet tall and weight 16,000 pounds or more. They grow slowly. After 15 years the plant may only be 12 inches high. Seedlings that sprout under a tree have the best opportunity to survive because this "nurse tree" protects the young plant from harsh sun and cold of winter. It also hides it from rodents and birds. After 30 years it can produce its first flower and fruit. After 75 years it can produce it's first branch or arm. Besides the desert trails, there is a trail called the Signal Hill trail that takes you into a more rocky area. This trail ends at petroglyphs that were etched by the Hohokam people who occupied the area from approx. 200 AD to 1450 AD.