In areas where it takes hold, Japanese barberry outcompetes every other plant. This means the flowers, trees and shrubs that provide pollen, nutrients and habitat which support native wildlife don’t have a chance to grow. Left unmanaged, barberry forms a thicket, upwards of 6 feet tall, of snarled and thorny branches. Once it spreads, it grows without interference because its thorns keep deer and other wildlife at bay. … More Take on Invasives: Japanese barberry