genus hydrangea: type genus of Hydrangeaceae; large genus of shrubs and some trees and vines with white or pink or blue flower clusters; sometimes placed in family Saxifragaceae
rosid dicot genus: a genus of dicotyledonous plants
split-brain technique: brain surgery on animals in which the corpus callosum (and sometimes the optic chiasm) is severed so that communication between the cerebral hemispheres is interrupted