Senita Cactus - Organ Pipe Cactus Nat'l Monument

Seven years ago I did a post on the senita cactus. I'd seen it on the Mexican side of the border in El Pinacate Gran Desierto south of Sonoyta and north of Puerto Penasco. I noted that there are senita cactus in the U.S. in Organ Pipe Cactus National Monument, but that it was an area not accessible to cars. 

Earlier this month I visited OPCNM and drove the South Puerto Blanco Drive for the first time. Then I noticed a road going north off that road into the Senita Basin and followed it. Nearing the end of that road I noticed some senita cactus from the car and got out excitedly to look at it. Then I flagged down a truck with people I'd been talking to along the way and pointed the senita cacti out to them and made the comment that these were the first senita cacti I'd seen in OPCNM. It was not until a few minutes later that the name of the basin came to mind, I connected the name of the cacti to the name of the basin, and I slapped my head for being so oblivious.  

Senita cactus.

Two separate clumps of senita cacti.

A young senita with very small arms. 

Obviously, the Senita Basin was named for the senita cacti in it and this road is a new road that did not exist when I visited seven years ago. 

The Senita Basin road is toward the bottom, right of center.

When I first saw the senita cacti I thought they were ugly, struggling organ pipe cacti, with brown branches and hairy ends. Now I recognize some of the huge differences between them. 

An organ pipe cactus is just right of center. Note that it is clumped fairly tightly and the arms are fairly uniform in length. 

A close-up of organ pipe cactus arms showing that they are fairly rounded and have many small ridges. 

By contrast, this senita cactus has arms that are much more spread out and arms that vary more in length.

The senita arms are more squared and have fewer ridges. 

The ends of many of the older arms are covered in massive amounts of spines that make them look like they are covered in hair and kind of old and unhealthy. That profusion of needles blocks 80% of the sunlight and helps the delicate growing ends of the senita to avoid damage from the sunlight. 

This was an exciting discovery for me.