I beg your patience and indulgence with a stupid question.
Years ago, I bought my first pulmonaria, 'Trevi Fountain'. It lived in a 1 gal pot just off my patio for those years. (I didn't know how well it would do for me, or if I would like it, or where I would finally plant it out - if I did like it.) Last year I picked it up to move it, and found that it had rooted into the ground. (I moved it anyway.) This pot was kept company by a collection of other pots in a sort of temporary (months to years long "temporary") nursery. (Just off the patio meant that they would not be "out of sight, out of mind".)
This spring, after we did some work elsewhere in the garden, I was finally able to plant out the 'Trevi Fountain'. It took the transplant like a champ (again, it had rooted down from its pot into the soil), and is thriving in its new home.
Yesterday I went to move one of those other pots (holding a fern, which I am also trying to figure out a spot for). It, too, had rooted into the ground.
But to my great surprise, when I moved that fern pot, there were 3 tiny plantlets of pulmonaria right around the base! (There is nothing else that I am growing, other than pulmonaria, that has that distinctive foliage.)
Now, I have no idea if these plantlets were volunteers that were self-sown by the 'Trevi Fountain', or perhaps by some 'Dark Vader' that I also had. (The 'Dark Vader' were in smaller 4" pots, and I don't recall exactly where I held them, or for how long, before they were planted out last fall.) OR (here is where I need your indulgence/expertise), is it possible that these plantlets came up from the bits of root left behind when the 'Trevi Fountain' pot was uprooted?
It's a stupid question, I know, and I apologize for my ignorance.

I just don't know how much of a root is needed to be left behind to grow a new plant, and if the roots coming out of the bottom of the pot would suffice. (The Plant Delights website does state that pulmonarias can be propagated by root cuttings.) I also don't know how easily pulmonarias will self-sow (but I have also read on plantdelights.com, and elsewhere, that they can).
Today I tried pulling up one of the plantlets which seemed to have a very long stem (I think it was trying to get out from underneath the fern pot, to where it could get some light?). I did so because I was trying to see if it was a distinct plantlet (and thus probably a seedling) from the other two. Unfortunately, I broke it off. It might have one bit of root on there (something sticking out from the stem), so I stuck it in a pot. I am afraid to touch the other two at this time - the soil there is pretty dense clay, hard to dig in, and there are a ton of tree roots in there too, from a weeping beech.
It is actually okay with me if a/some pulmonaria takes up permanent ground-level residence in that spot (about 6 inches over would be a better location, lol), as it really is a lovely plant, and its spring flowers are very welcome there. I just would like to know (barring distinctly different blooms), how to figure out what the heck these little plantlets are!
Any ideas? (Thanks for your help!)