To help with understanding t/c's consider hostas, which we all know are mostly tissue cultured. When a new type/style/combination of variegation comes to market it is called a 'sport' which is another way of saying it was a seedling found in a batch of tissue cultured plants; see Mark Zillis' really good "The Hosta Handbook" 2000 where he lists "seedlings (shown as pod parent X *) and sports (no genetic info).
I was the 'beneficiary' of a missed sport of athyrium pictum 'Burgundy Lace' over twenty two years ago when I spotted a different one on a huge bench of athyrium pictum. It was several years later that this selected form was identified and sold as 'Burgundy Lace'
