Because even the most stable of variegates sometimes loses variegation or changes the form of variegation we must look at the way that these cultivars are currently named so that they can easily be identified.
The only reference in the ICNCP rules is in Section 17.15 which states: "The words 'variety' (or var.) and 'form' may not be used in new cultivar epithets. However, when var. denotes variegated the epithet is established with the word 'variegated' written in full". This is not that informative perhaps because variegation plays a very small role in the general world of plant cultivars. Variegation is much more specialised in the Bromeliaceae where the following non-Latin adjectives could apply:
There are, of course, other adjectives that could be used but regrettably, I do not see us getting a general concensus on what ones to use.
The ICBN rules cover like-plants from the wild where the "normal" version is described at species level and the variegated form at the next level eg. Aechmea coelestis v. albomarginata.
If you have a plant without variegations it becomes just Aechmea coelestis! This is easy to understand.
How Do We Follow The Instability Of Cultivar Variegates?
The word 'Sport' has been in horticultural use for many years but has rarely been formally applied to Bromeliads. A 'Sport' is defined as a visible asexual mutation and occurs in bromeliads where offsets (or pups) are different to the 'Mother' plant. To my mind there is a closer relationship between a 'Sport' and a 'Mother' plant, than that between siblings in a grex and we should record this fact when it occurs.
While variegation can occur in the seed raising stage this is NOT included in this definition.
United States Plant Patent law covers all offsets of a patented plant whether sports or not but is broken by seed raising and this seems to be a firm basis to start from.
The phenomenon of 'Sporting' has become more prevalent in the past 10 years or so because of the avalanche of named variegated plants which are notoriously unstable. Just what do you do with an offset that is different from 'Mother'? To be strictly correct this should be destroyed but in reality they are not destroyed but even nurtured!
As an example, Aechmea 'Ensign' (See Baensch Blooming Bromeliads p44) should be an albo-marginate form of Aechmea orlandiana. It was raised by seed where the mutation occurred. Note that Aechmea 'Ensign' is not a sport of Aechmea orlandiana! A sport of Aechmea 'Ensign' is 'Reverse Ensign' which has a white median line. These will be linked in the Bromeliad Cultivar Registry by a 'Sport' indicator. Any offset of Aechmea 'Ensign' which is not albo-marginate (or reverse) should in my mind be called Aechmea 'Ensign' sport until such time that it 'stabilises' and someone gives it a name. Even if it loses its variegation it should still be called Aechmea 'Ensign' sport and NOT Aechmea orlandiana because it still retains the erratic genes and could easily revert back to an Aechmea 'Ensign'.
Many of the registered variegated Neoregelias could well have developed as sports and not as siblings within a grex but the Registration form did not allow for this situation. This omission has now been rectified.
Plants that have sported directly from a species include Billbergia 'Perriam's Pride' which was originally Billbergia distachia.
So please use the word 'Sport' as a temporary measure to cover aberrant offsets. A more direct option is to use the epithet 'Novar' which indicates that a previously named variegated plant has lost its variegation and which could well be just a temporary aberration. For example Vriesea 'Gunther Novar' which has a propensity for losing its stripes!
This solution will make it easier for the 'Show Bench' to accept the inevitable non-stable plants that do not agree with the original description or photograph by the quick addition of an epithet. It will also help sellers (and purchasers!) of a plant to know its true relationship with its 'Mother' in that temporary period before possible new naming.