There has been lota of talk here about hickory over the years.
The link above is a good one.
I dont recall any mention of having to have two different types (for pollination) like you do with pecans.
Hickory and pecan can cross polinate… my daughter bought a home out in the country a while back and she has a bitcon in herfront yard… a cross of bitter nut hickory and pecan. Not good for eating.
Shagbarks grow all over here in my county but you rarely see them above 750 ft elevation… they prefer lower elevation… hollow bottoms or very low on the hillside.
Love foraging and eating the shag bark hickory nuts. We dont have shellbark here in my county.
TNHunter