Allergy-inducing plants in Europe can be divided into five main areas:
- Northern Birch, grasses
- Central Deciduous forest trees, birch, grasses
- Eastern Grasses, mugwort, ragweed
- Mountainous Grasses, trees
- Mediterranean Grasses, Parietaria, olive, cypress
Grass pollen is the most important allergen in Europe. As the cross-reactivity is extremely high amongst nearly all grasses, for the grass-pollen sensitive patient it makes no difference, which grass pollen she/he inhales. Only the pollen of cultivated rye has a higher allergen than the pollen of wild grasses. In fact, the high meadow grasses like orchard grass or rye cause the majority of symptoms.