If they are both from the same species, and most snap beans, both pole and bush, are from the phaseolus vulgaris species, then they can cross. Having said that, I have to admit, that in 24 years of saving bean seeds, I might have seen such a cross, just once. And, the first couple of years I didn't give my beans any isolation distance. So crosses with these beans, though possible, are not awfully common.

If you can give the two kinds of beans even 15' of space between them, especially with something tall growing between them, then you are probably not going to see a cross. Also, if you can't do this, I wouldn't discourage you from saving seed. Just try to do it in the future and be sure to weed out any plants with atypical growth or fruit, in the next generation.

I'm pretty sure that some varieties of beans are more prone to crossing than others. This year I'm trying to make a cross between two greasy beans, so I planted them, mixed, on the same poles and will replant seed next year. But even having done that, I expect that at least 99% of what I plant next year will still breed true to the original two varieties.

Hope this helps!

George
Tahlequah, OK

That helps a lot! Thank you George.