The North American herb, Echinacea, grown and used widely in Australia.
Echinacea is often known for its "buzzing" in the mouth effect. This is created by the chemicals in the plant that provide its immune boosting effects. If your echinacea product doesn't produce this, chances are its not very good. The chemicals, known as alkynamides are present in the root and flower and part of the plant's defence against infection.