As I have mentioned elsewhere, trees in the legume family have funny swellings on the leaves and these are at the base of the leaf blade where it attaches to the petiole.
Fruit is a persistant pea-pod, 2-3" long and very thin.
Fall color is a bonus. The species has yellow fall color and when you mix in some purple you get some really nice shades of reds.
Misidentification: If there are leaves not likely. If in bloom, well you may not know the leaves are purple but you will not mistake a redbud in bloom for anything other than another redbud. Cercis occidentals is our native redbud and is almost always smaller and seriously more multi-stemmed, almost suckery. You will see lots of our native along highway 1.
everywhere, I will try to keep my eye open for really nice old ones.