Wild plum comparison and Canada plum seed source

comparison of wild plums, each of these from a different tree. in the first photo the front row are Prunus nigra (Canada wild plum) and the back are Prunus americana (American wild plum). All of these likely have some amount of hybridization, and in that there's natural variation in the fruit. typically the Canada plum have more of an oval shape and the american are more round, and the leaves and distinctive, the Canada plum has a leaf margin with small double bumps, and american plum leaves have a jagged serrated leaf margin and are more narrow with a thin point. in the second photo left to right: an americana selection (#1) locally in our nursery grafted to chokecherry and does well as interstems, then a seedling plum in a small town nearby, the small red one is a wild plum that ripens early - so those 3 all present strongly as american plum. the last 2 are canada plum from old nursery row, and then the large on on the end is a seedling. I keep track of these seedlots, since it also depends on the other plum trees in the area (the pollen parent) you get more or less variation in the seedlings from these lots. the second last one is what I offer as Canada plum seeds on our shop, because all of the trees in this row are very similar, the seedlings will likely be very close to these and are very typical Prunus nigra. the 2nd and 3rd are very americana, but maybe I'll offer the seedlots separately since one will probably produce a larger plum - both will be good pollinators.