Only certain rhododendron species, such as Rhododendron luteum and Rhododendron ponticum, contain a natural neurotoxin called grayanotoxin, which gives mad honey its psychoactive properties.

Members of a project established in Connemara and South Mayo to control the spread of Rhododendron Ponticum in the ...

Common species include Rhododendron ponticum, Rhododendron arboreum, and Rhododendron catawbiense. There are also thousands of cultivars, bred for specific traits like flower color and bloom time.