Common buckthorn is an invasive shrub commonly found across southern and central Ontario. This exotic shrub is native to Eurasia and is believed to have been brought to North America sometime in the 1880’s to be planted in hedgerows. It spreads readily by seed and can quickly transform an old field to a buckthorn thicket within a short period of time. Removing this shrub can be quite challenging when it occurs in dense patches due to its thorny twigs. For this reason, eradicating populations before they become established is strongly recommended.