Alder leaf distortion

Alder leaf distortion

Observation - Alder leaf distortion. Description: There were several of these distortions in the leaves of what I believe to be a young alder at the edge of a freshwater pool. My intial thoughts were that they were galls but I cannot find them in the the Plant Gall AIDGAP guide. Any ideas please? Not sur

There were several of these distortions in the leaves of what I believe to be a young alder at the edge of a freshwater pool. My intial thoughts were that they were galls but I cannot find them in the the Plant Gall AIDGAP guide. Any ideas please? Not sure which group to place the observation in so will try Plants first.