|Saguaro (Carnegiea gigantea)|
DESCRIPTION: Commonly grows to 40' tall or more and may be branched (called saguaro "arms") or unbranched. Flowers are white (3" in diameter) and bloom mostly May - June. Fruit are red to reddish-purple on the outside and bright red on the inside.
NATURAL HISTORY: Saguaros may live over 200 years and grow to heights over 75'. Growth rates vary, but in the Tucson Mountains, saguaros commonly begin to flower at the age of 55 (about 8' tall) and grow arms when they are between 50 and 100 years old. Arms function to increase reproductive potential because the flowers/fruits are borne on the ends of stems (main trunk and arms). Their pleated stems allow them to expand and contract as they store and use up their water. Flowers are pollinated by bats (e.g., Southern [Lesser] Long-nosed Bat), birds (e.g., White-winged Dove) and insects (e.g., bees). Fruits are eaten by many animals (including humans). Seeds are gobbled up by ants and other animals, and then seedlings are vulnerable to freezing and other hazards (so they generally only grow successfully under a nurse plant). Saguaros are critical in the culture of the Tohono O'odham people.