Rock figs (tescalama): Ficus palmeri and F. petiolaris

Rock figs are a legacy of the tropical origins of the Sonoran Desert. They are a kind of strangler fig. Tropical strangler fig seedlings start life as epiphytes high on the branches of host trees. The fig roots encircle the host's trunk and eventually reach the ground. The roots then enlarge and squeeze the host tree's trunk while the upper branches overshadow it and starve it for light. The host dies and rots, leaving a hollow giant fig tree.

There are no trees in the Sonoran Desert large enough to host a stranger fig seedling. Desert rock figs took to establishing on cliff faces and "strangling" rocks. They may live as dwarfed saxicoles their entire lives. But if their roots eventually reach the moist soil of a canyon bottom, they will grow into large trees.

Roots of a tropical strangler fig (Ficus cotinifolia) encircle a sabino (Montezuma cypress, Taxodium distichum mexicanum) near Alamos, Sonora.

This rock fig (Ficus palmeri) in central Baja California grows on a desert hilltop boulder. It will never find water and become a tree. It appears to be ancient; it may have clung to life here for centuries.

Roots of a tescalama (Ficus petiolaris) "strangle" a cliff on the Rio Guajaray, Sonora.

The roots of this tescalama have reached a streambed and the plant has grown into a large tree near Alamos, Sonora.