Sycamore (Acer pseudoplatanus L.) is a naturalised exotic species that grows well on a wide range of sites across the island of Ireland, usually as a minor component of mixed woodland. The time of introduction is uncertain, and it is currently thought to have arrived in Ireland as late as the sixteenth century but has become well established in the last 200 years. Sycamore is a hardy species being tolerant of wind and salt-spray, late spring frosts, shade in earlier years and can also grow on sites contaminated with heavy metals. At present, it is threatened by no major pests or disease but is highly susceptible to damage by grey squirrel. It prefers cool, humid sites and can produce prolific amounts of seed, which often facilitates natural regeneration.