This is a picture of Taphrina farlowii on a black cherry at Rockburn Branch Park near Elkridge, Maryland.
NOTE transparent, exit slit not obvious on bottom of gall, does not go through leaf surface like most macrodiplosis galls.
Q. phellos. Sending to Forbes lab.
Q. alba. Sending to Forbes lab
Q. stellata. Multiple galls on the same tree. Sending to Forbes lab
Q. alba. Sending to Forbes lab