^{(Photograph = Ferocactus spines, David Wicks)}

Introduction

Cacti are remarkably adapted to survive drought, sometimes extreme drought of many months coupled with temperatures of 90F to 100F. Their shapes reflect their adaptations.

The Details

Cacti are often spherical or tubular, good shapes for preserving water. Most cacti have a waxy cuticle-covering that prevents loss of water; this cuticle often gives them a matte look. They have spines, which are good for repelling animals but also for providing shade to the green parts. Some cacti have flat stems that are good for capturing light. Many cacti grow in dry grasslands or areas that are only seasonally dry; they don’t actually grow in harsh deserts.

Additional Reading: Shapes of Cacti