Just out of curiosity, is the albino seedling diploid or tetraploid?
There are many many genes that need to work normally for a plant to be green. Mutations (errors in genes) are very rare, say one in a million. But because there are so many genes involved albino mutations are the most common in plants. The mutations cause the genes to not work correctly and that sometimes causes the green pigment to not be made or to be destroyed.
Usually (or most) of the mutations are recessive (the albino characteristic is not seen unless a diploid carries two bad copies or mutant copies of the gene) and usually only one of the many necessary genes needs to mutate. But both copies of that gene must be mutant for the plant to be 'albino'.
Stella de Oro carries at least one such mutant gene - so we could describe Stella's genetic make-up (its genotype) as Aa meaning a is the mutant or 'bad' copy of the gene for albino and A is the good copy that works properly. Since Stella has one good copy it is green. But if you self-pollinate Stella then some of the seedlings will be albino. Some other cultivars also carry the same albino mutation (especially others that are related to Stella)
A cross of a green-leaved diploid daylily carrying the mutation Aa with a green-leaved daylily carrying the same mutation Aa will produce some seedlings that are green and are genetically AA or perfectly normal, some that are Aa and are green but carry the mutation and some that are aa and are albino.
In a simple perfect world - one quarter of those diploid seedlings would be AA, one half would be Aa and one quarter would be aa. But things are not usually simple. Although albino is usually recessive and two copies are required to be visibly albino that does not mean that the Aa seedlings are perfectly normal. They are green and they may be perfectly normal looking green when they grow. But. In the seed in the pod the embryo has to grow from a single cell to a tiny baby plant (more or less a huge oversimplification). To do that it tends to need the A gene to work reasonably well and that does not always happen. So some of the Aa embryos may die and/or not germinate, etc. And there may be quite a few of the aa embryos that do not even make good seed. So one does not necessarily see the expected Mendelian ratios of 3 normal to 1 albino expected from crosses of Aa x Aa.
In tetraploids the genetics is even messier but follows similar reasoning.
