and the size of a "specimen plan" depends also on the species or hybrid, so it is not a clear definiton. For example, C. skinerii is a plant that tends to grow quite easy, and it is very common seen as a quite large plant, so a "Specimen" must be very very large!!! A species of Hybrids which is very slow grower, or normally has a small size, does not need to be very large to be considered a "Specimen". It is always a relative designation... (well, that's my way of interpreting the term
)
There are some AOS Judges here in OB, they can for sure give you a much better definition...