This is a very common cactus is Big Bend. During the 2001 desert bloom these were blooming profusely and were a beautiful magenta color. This was shot at mid-altitude near the the road to the Chisos basin.

Photo Details: Nikon N90s, Nikon 85/2.8 Tilt Shift, Velvia, f11@250, Manfrotto CF4221 w/ Kirk BH-1, diffuser