May 8,   Beaver Brook Reservation, Waltham
A probable nothospecies--a spontaneous hybrid of European and Asian barberry. Leaf margin entire, like it should be in Japanese barberry. In the hybrid, flowers must be in racemes with a shortened axis, containing more than 4 flowers (flowers mostly more than 4; yet no inflorescence axis observed; spines not photographed; could be just a cultivar of Japanese barberry).