I have to say Chokecherry (Prunus virginiana) is not at all invasive. Not at all. But it most certainly is not a single trunked tree.
It is a shrub, and not a single stem shrub either... I've planted a number of them in my yard. They have wonderful arching spikes of flowers, provide berries for the birds and are a good host plant for butterflies as well. I expect mine to get a few stems, I would be happy with three or four (and don't really expect to many more as they are in part shade).
It is a suckering shrub and in full sun can produce a nice bushy growth but in full shade it often occurs single stemmed... Its certainly not as aggressive as many other garden shrubs available, certainly nothing to deem being called invasive.
When going to the nursery you have to do YOUR own research and scientific names are a must.
