Hickory tree has strange bumps on the leaves.
Today when I cut the grass I noticed bumps all over the leaves on my hickory tree. I have never seen this in the past
Queen Anne's County Maryland
These are probably leaf galls, which are not usually a disease, but the reaction of the leaf to activity by insects, mites, etc. There are many, many kinds of galls that appear on many species of trees. The vast majority of them are harmless. Here is information from our website: http://extension.umd.edu/hgic/shade-tree-galls
You can search 'hickory leaf galls' online if you want to find the type of gall your tree has. You can also send us photos to id.