A. retusus LRM178,
a large plant with broad flat tubercles.
A. retusus LRM178,
a typical flowering specimen.
Comments
This is one of the three locations where we have seen this species in the
state of Tamaulipas. The plants here have very broad triangular tubercles
with a small areole at the tip and white flowers. The plants were found
on the low southerly slopes of moderately high limestone hills.