While Judy and I were visiting Organ Pipe Cactus National Monument recently, we stayed in Puerto Penasco, about 60 miles below the U.S. border. We took several detours into El Pinacate Gran Desierto and while driving there found what we thought were badly damaged organ pipe cacti. Many stems were brown and limp and we attributed it to the harsh summer conditions in that area and perhaps lack of water.
Then I noticed that the stems looked a little different and decided they might be a different species of organ pipe cactus.
Now that I am home and have researched it, I have determined we were seeing a completely different species of cactus: the senita cactus.
The senita has pale pink flowers that open after dark and close around dawn. They are pollinated by a small moth. The fruit is red and spineless. They are prone to damage from cold, which I assume is what causes the browning of the stems. They are only found in Organ Pipe Cactus National Monument very near the Mexican border in an area that is frost-free and not now accessible by car. They are much more common south of the border in Sonora where we noticed them. If I'd known they were a different speicies, I would have taken more pictures and paid more attention to them. It gives me another reason to go back!