Canada plum

Prunus nigra. A native species to Canada, it is most often used as a pollinator for other plum trees. It also produces (small) plums that can make a great jam or jelly, and it can be used as a rootstock for plums and maybe even peaches. Hardy to zone 2, this small tree grows to 15 ft tall, and puts on a show of a profusion of beautiful flowers in the spring.