Desert extremes would wither most plants, but not cactus. Able to withstand infrequent rain and harsh temperatures, each employs its own strategy for survival.

Gently sloping alluvial hills below the Tucson Mountains in Arizona create the ideal habitat for 25 different species of cactus which grow here, the most famous of which is the saguaros, that grow in stands so dense that they’re known as cactus forests.

Saguaros grow very slowly at first – an inch or so during their first six to eight years. It may be 70 years before they sprout branches, known as arms. They reach full height, 40-50 feet, at about 150 years and some may reach 75 feet with long, woody ribs which support their multi-tonne bulk.

Seedlings have the best chance of survival when sheltered by “nurse trees” like mesquite, ironwood or palo verde. As rain falls, the saguaros cactus collect water through shallow roots extending about as far outward as the main trunk is tall. As the cactus soaks-up water, accordion-like pleats in its trunk and arms expands to allow for storage in the spongy flesh.

In early summer, cream-coloured flowers appear and white-winged doves, lesser nosed-bats, honeybees and moths feed on the nectar and pollinate as they go. In July the saguaros produce deep-red fruit providing food for both animals and humans.

Me at the Saguaro National Park in Tucson, Arizona pictured with a saguaro cactus that is 102 years of age! 

Pictured left: a Fish-hook barrel cactus; right: a Chain-fruit cholla cactus, part of the cactus family of the Saguaro National Park which was an absolute delight to visit.