Cattleya walkeriana var. coerulea

A compact, but sprawling plant, C. walkeriana is as suitable for mounting as it is for window-sill culture -- as long as you're prepared to put a bit of extra care into it.

This picture of the coerulea (blue) variety was taken at H&R Nurseries in Waimanalo -- I purchased a couple of them and could never get them to grow and bloom quite as well as these.