Hi,
I found a group of plum trees from suckers in Heidelberg/Germany and assumed that they are damson plum (Prunus domestica ssp insititia) They all had a very slender growth form (usually more than 10x as tall than wide). since they were growing close together i attributed that to competition. Since then i have seen them several times growing from suckers from rootstock and they were always incredibly slender even when growing with enough space between them. Here is the original video:
https://m.youtube.com/watch?v=sP6kUjpO4BMSince the fruits are pretty good and the plants are obviously very vigorous i wonder what the variety (always used for rootstock) is and if it would be worth promoting it for small gardens