Plantago Major consists of the dried leaves of Plantago major L. (Fam. Plantaginaceae) gathered during the flowering period. The plant is a native British herb, with a basal rosette of leaves which abruptly contract into long petioles, bearing a long cylindrical spike up to 50 cm tall, green-brown with lilac and yellow stamens protruding.
The structure of the Plantago Major plant includes a remarkable glycoside of the monoterpene class (iridoid) called Aucubin.
This glycoside has been studied and numerous scientific papers have been written about this particular member of the monoterpene family.
The anti-toxic, anti-inflammatory and expectorant characteristics suggest why the plant is useful in lung disorders, and as inferences as to the effect of the Plantago Major on smokers. Exact cause and effect relationships are not yet fully understood. However, the above suggests real reasons for the noted effects on smokers.