Cacti in the Valley

We live right in the middle of the Sonoran Desert. This area stretches north to the Mogollon Rim, south into the Mexican state of Sonora and down the Baja Peninsula, west near San Diego, Calif., and east just past Tucson. All cacti are native to the Western Hemisphere. The range of growing cacti is limited by freezing temperatures and by elevation. 

All cacti are succulents but not all succulents are cacti. Succulents require little water and are drought tolerant. Cacti generally require eight hours of sunlight daily. Features of cacti include a waxy cuticle, fleshy leaves, stems or roots for water storage, and a large shallow root system that spreads out. Some succulents may have hairy or small spines and remain rubbery in texture.  Cacti have areoles, small nubbin-like structures found on the body. 

There are more than 1,000 cactus varieties. Common varieties are identified by shape. 

The totem– or column–shaped stems have a vertical growing pattern. Cacti varieties of this shape are the Organ Pipe (Stenocereus thurberi), Saguaro and Golden Torch (Trichocereus spachianus). 

The cylindrical stems are low-growing and sprout in clusters or mounds. These include pincushion, pineapple-beehive, hedgehog and barrel stems. This group includes the Arizona Fishhook Pincushion (Mammillaria grahamii), Fishhook Barrel (Ferocactus wislizeni) and Engelmann Hedgehog (Echinocereus engelmannii). 

Segmented stems are shrubby or tree-like. They grow in new stem segments, or joints, from previous years’ segments. This group includes the flat, paddle-shaped Engelmann Prickly Pear (Opuntia engelmasnnii) and chollas such as the Buckhorn Cholla (Cylindropuntia acanthocarpa). 

Stick-like stems are cylindrical– like rods and the sticks are square or round. Desert Night-blooming Cereus is most common. 

Arizona is a great place for cactus lovers. Our climate is conducive for growth from the hot arid south to the cooler temps and grasslands of the north. 

The Saguaro Cactus (Carnegiea gigantea) is the king of desert cacti. It is columnar and tree-like, growing 1 to 1.5 inches a year. The branches, or arms, take 50 to 70 years to appear. With lower precipitation, it may take a century to sprout branches. At 35 years, it produces flowers. The Saguaro’s white flower is Arizona’s state flower and houses the state bird, the Cactus Wren. An adult plant is considered to be 125 years old and could weigh six tons or more.