Beautiful flowers on a plant you don't often see flowers. Very nice Alain. What size is the square pots you show in most of your photos. I often try and judge the size of the plants in the photos and knowing most of the pots shown are the same and their size will help. This is apparently another of those small rare Mexico that grow on steep slopes or in the case of a few species, on vertical walls. I've enjoyed all of the great plant photos you've posted over the past weeks. Thanks.
The plant in the round pot is a bit tatty but flowers very well. The square pot is 2 3/4 inch which I use a lot. They are BEF pots - please see http://www.hartley-botanic.co.uk/featured-blogs/lila-das-gupta/mystery-in-the-greenhouse-bef-pots Have you been to Mexico to look at plants?