On Bitternut/C. cordiformis sapling.
Found as well on a mature C. cordiformis elsewhere in Green-Wood today: https://www.inaturalist.org/observations/217141929
One of two on leaves of low-hanging branches of mature Bitternut/C. cordiformis.
Also found today on a Bitternut sapling elsewhere in Green-Wood: https://www.inaturalist.org/observations/217143239
Q. rubra (I think). Five galls from the same tree. Sending to Forbes lab.