One species of this genus is widespread in the neotropics from Mexico to Brazil, but uncommon in collections. It is Dim. emarginata. The other one is probably extremely rare and limited to Mexico, it is Dimerandra longicaule.
I lately bought this plant from a friend, who raised it from seed, so I earn no merits. It is compact, not more than 20 cm tall, I didn't notice a scent.