Since 1900 Aronia has spread vigorously in some nature reserves in The Netherlands. Almost all Dutch plants show characters intermediate between A. melanocarpa and A. prunifolia. From the fact that Aronia has been introduced into The Netherlands for horticultural purposes, and from the proved possibility of hybridization and back-crossing between A. arbutifolia, A. melanocarpa, and A. prunifolia, combined with the great variability of the Dutch populations, it is concluded that almost all Aronia plants in The Netherlands form part of a variable hybrid group that should be given the name A. x prunifolia (Marsh.) Rehd. Only at the site of its first introduction into The Netherlands (near Domburg, Zeeland) A. arbutifolia has been collected recently.