I don't remember exactly where I took this one, but it was somewhere in the Tucson Mountains. Typical of these mountains are the rocky outcrops, palo verde trees (they have green trunks that have chlorophyll and perform photosynthesis), and the saguaro cacti (the tall cactus on the right, for example.) This cactus has some apparent scarring on it. Most likely, these are cactus boots, which are openings that are lined with scar tissue. These are a favorite home for small animals such as owls and other birds. When the cactus dies, the boots will come out intact, and are regarded as decorative. © Pat Goltz Thank you for your comments. I greatly appreciate them!