Hawthorn has been used by herbalists for hundreds of years and is now one of the most popular herbs in the Western world with many publications reporting its significant properties. Hawthorn s active ingredients include a range of flavonoids including rutin and proanthocyanidins which are found in high quantities in the leaves and flowers of Hawthorn . LambertsHawthorn extract is obtained from the aerial parts of the plant and is standardized for its flavonoid content (2%), making it a particularly potent product.