Barberries and Wheat

If you look at the entries in the Flora of North America for barberry species (Berberis), each notes whether it hosts Puccinia or not. That is not a common sort of entry into a plant description; Puccinia is a fungus, the genus of wheat rusts. (Examples  Berberis amplectens, Berberis aquifolium , Berberis bealei and every other one: scroll down to Discussion).

Japanese barberry

Here's the story: