The Echinomastus forms found in Arizona, in flower, all in one handy blog post.
Echinomastus intertextus (disclaimer: a cultivated plant, not a habitat photo, and not specifically the form found in southeast AZ):
Echinomastus erectocentrus, from near Benson, AZ:
A rescue plant of Echinomastus erectocentrus from a nearby location:
The first of two stars of this particular post, Echinomastus erectocentrus 'acunensis' from Pinal County AZ:
bizarre extended green pigments in this one:
a lot of variety in the flower colors:
Another star, Echinomastus johnsonii 'lutescens' from Yavapai County:
And last but certainly not least, Echinomastus johnsonii, from northern AZ, plants sent to me by a friend there, salvaged from a construction site:
and there you have it. From Cochise County to Mohave County. Hundreds of miles of driving and 8 months of field work. Can't wait for next year.