This exceptional species is newer to cultivation and as its name would indicate, covered in mountainous bumps (bullae).  It is distinctly patterned with wide silvery white striping along the largest leaf veins.  Between are olive-purple bullae which fade to a more silvery-green with age.  This is a slower growing species, found growing on limestone slopes in Vietnam.

Plants are well rooted and growing in 4″ pots.  The last photo is representative of the size plants available.