After many years of searching, in an old book I finally found a drawing that matched what we called a "beer apple" when I was a kid: a crab apple with fluoresent-red, oblong fruit (which makes superior jelly), that typically bears on alternate years: according to the drawing, this might be Malus dolgo, which apparently is often used as very hardy rootstock but seldom grown for itself.
There are a few of these "Beer Apples" in Great Falls MT, but I've never seen one anywhere else.
Anyone know anything more about them?
~REZ~