About 1919 cuttings of the North-American poison-ivy, Rhus radicans L., were planted to consolidate a dike between two lakes in the southwestern part of Friesland, Morra and Vogelhoek. The species has completely established itself there, and at present as a real liana, it covers nearly the whole dike and its willow-vegetation over a distance of about 500 m. To some extent the poisonous plant means a danger to the inhabitants of the neighbouring villages, especially to the children, who go there swimming and picking blackberries. Some cases of an obstinate eczema have already occurred. Parents warn their children against the “poisonous trees” of Vogelhoek!