Heartnut pollination

A few years ago I planted a “Stealth” heartnut, but only this year realized that it will need a separate pollinator. I’ve since planted a 2nd tree, but the older heartnut is blooming for the first time and it will be a long time before it’s pollinator tree is of any use.

I’ve got legions of black walnuts in the area, are they able to pollinate heartnuts? I took some walnut catkins and lightly brushed them over the heartnut flowers, but I’d like to know if that actually has a chance of working.

White walnut will pollinate it. Not sure about black, but I do not believe so.

I’ll keep my eyes peeled, but I’ve never seen a white walnut in my area.