The subspecies 'petrophila' has brilliant green-yellow flowers and 1-2 central spines per areole.
The subspecies 'arida' has pale ...Read Moreyellow to cream colored flowers and 4-7 thin needle-like central spines per areole.
The subspecies 'baxteriana' has yellow flowers and just one central spine per areole.
The subspecies 'petrophila' has brilliant green-yellow flowers and 1-2 central spines per areole.
The subspecies 'arida' has pale ...Read More