In trying to get more of the pure blue form I once crossed two blue plants, carefully isolated from other colour forms. I was surprised when one or two of the resulting seedlings turned out purple (i.e. var. violacea). Perhaps this isn't so surprising on reflection - this species has been in cultivation a long time and with no re-introductions from the wild. Seed sent to exchanges is often open pollinated and from collections where all three colour forms are present. I would guess that as a result all the colours are "in there" somewhere genetically speaking and will pop out from time to time. Paul Cumbleton