I only know how to separate them when they are blooming. We have four common species (and two very rare)
A. arborea: common serviceberry
A. canadensis: Canadian serviceberry
A. laevis: smooth shadbush
A. spicata: dwarf serviceberry
The rare ones:
A. sanguinea: roundleaf shadbush (this is a northern species)
A. bartramiana: Bartram's shadbush (a more common northern species)
When flowering:
- leaves 1/4 grown: dwarf
- leaves much less than half grown: common
- leaves half grown: smooth
- leaves still folded: Canadian
Leaves:
- nearly smooth: smooth
- hairy: the other three
Leaf tip:
- pointed: common or smooth
- round-tipped but maybe with a bristle: Canadian
- any shape: dwarf
Leaf base:
- tapered: common, Canadian, or dwarf
- not tapered: smooth or dwarf
Flower stem:
- silky: common
- hairy: Canadian
- smooth: smooth
- with thin hair: dwarf
So:
Common: tiny leaves at flowering, very hairy, pointed on both ends
Canadian: larger leaves at flowering, with round, maybe bristle-tipped ends, hairy
Smooth: moderate leaves at flowering, everything is smooth, leaf base not tapered
Dwarf: tiny leaves at flowering, very hairy, a much smaller plant than the common.
Roundleaf: has rounder leaves with veins that go all the way to the teeth
Bartram's: smooth, and with very few flowers
