The St John’s wort grows at shady places
The St John’s wort grows in whole Europe. The plant prefers all areas in the shadow that are at the edge of the forest or near low shrubs. However it can also grow on a shady place in the middle of the pasture. And then you will never find one single plant but always a big number of St John’s worts!
In some areas there is a professional cultivation of the St John’s wort. The plant gets sold as a medicinal plant against depressions.
Especially white horses are in danger of this plant
For most of the animals this plant does not have any or only light toxic effects. However a consumption of the petals can cause a hemolysis. This means that the red blood cells get damaged until they finally cannot transport the oxygen in the blood of the animal anymore (anemia). Especially white horses are in danger of this life-threatening process.
White animals only provide a low number of pigments in their skin that can protect them from the sunlight. If the horse eats the petals of the St John´s wort the dangerous substance hypericin enters the organism and the blood. The sunlight can easily go through the skin and then activates this substance in the blood. This causes flush and very painful ulcers.