The subspecies 'rigidissumus' has stems that reach over 4 inches thick with 15-23 radial spines per areole.
The subspecies 'rubisp...Read Moreinus' has stems that only get about 2 1/2 inches thick with 30-35 radial spines per areole. The spines are also more Ruby/pinkish colored compared to the 'rigidissimus' subspecies.
The flowers on both are bright pinkish-red or magenta or red with white throats.
I've seen these growing in the wild on the West Ruby Road Trail in Arizona (South of Tucson), off of Interstate 19 through to Ruby, AZ and on to Arivaca, AZ.
The subspecies 'rigidissumus' has stems that reach over 4 inches thick with 15-23 radial spines per areole.
The subspecies 'rubisp...Read More