Lonicera X bella is an introduced, aggressive hybrid shrub that occurs in Wisconsin and much of central and eastern North America. Both parent species occur in a wide variety of habitats in their native ranges, as does this hybrid in North America. Ordination, by principal components analysis, indicated that the dimension of maximum morphological variability is that which best separates the parent species. Physiological tests and transplant gardens revealed no evidence of ecotypic differentiation in the populations studied. Selection for heterosis is suggested by certain morphological characteristics of the hybrids, by the high freqency of hybrid individuals that are intermediate to the parents, and by the ecological behavior of this shrub.