This photo speaks volumes about the adaptations among desert plants to deal with the critical limiting factor in all their lives, water. In the foreground are the bare branches of copal (Bursera hindsiana), a tree that is "drought deciduous" as a means of conserving water. When water is scarce it will drop all or most of its leaves and go dormant until enough moisture is in its environment to grow new leaves.
Behind the copal is a large stand of galloping cactus (Stenocereus gummosus), also known as the pitaya agria or the sour pitaya (for its highly prized fruits). This cactus has all the usual adaptations of the cactus tribe: leaves modified into spines, photosynthetic stem tissue, night-time absorption of carbon dioxide that is saved as an acid in its tissues and utilized in photosynthesis during daylight hours and of course spongy tissue capable of storing large quantities of water. Its common name, galloping cactus, comes from the way in which the long arms bend down to the ground, root and begin to grow up again as the entire plant performs a slow-motion gallop across the desert.
In the background right is a cardon (Pachycereus pringlei), the largest cactus in the lower Sonoran desert and a close relative of the saguaro cactus of the American southwest. It is slow growing when young but as an extensive, shallow root system develops in older plants some arms may grow a foot a year.
In the background left is an evergreen tree known as palo San Juan (Forchammeria watsonii). It survives the desert by having leathery leaves with in-rolled margins that cut down on evapo-transpiration of internal moisture. It produces a small fruit with edible pulp late in the summer.
Our hike was a wonderland of these and numerous other desert plants each displaying adaptations for survival in a beautiful land surrounded by a beautiful (if not always calm) sea.
