The oak tree , or "carballo" in Galician, is the Galicians' sacred tree. Its shade is beneficial and its interior houses the "ray stones" which have curative properties.
Before, to cure a sick child, a crack would be made in the trunk and he or she would have to pass it three times. Afterwards they put a rope around the trunk and if it joined up it meant the sick person would get better, otherwise.... Others simply hugged the trunk to be cured.
Other trees and plants such as the holly tree and the walnut tree also have magical and curative properties. However, it is believed that the shade of the walnut tree can be harmful.
There are many more rituals which use plants for various purposes. "Wise women" and "menci˝eiros" (a person halfway between a doctor and a healer) are experts in their use.