Crataegus oxyacantha, traditionally praised by Greek herbalist Dioscorides, gained widespread use among herbalists across Europe and America. Today, it is recognized as a cardiotonic agent for treating functional heart disorders. Contemporary research has confirmed these traditional uses by demonstrating the extensive beneficial effects of Crataegus extracts on cardiac function. The adaxial surface of Crataegus laevigata leaves appears dark green to brownish-green, while the abaxial side is a lighter greyish-green with a pronounced reticulate venation. The leaves of Crataegus azarolus and Crataegus nigra are densely pubescent, whereas those of C. laevigata, C. monogyna, and C. pentagyna are mostly glabrous or have few trichomes. The main bioactive constituents in the leaves and flowers include flavonoids (primarily flavones and flavonols as glycosides), flavan compounds such as oligomeric procyanidins, catechins, triterpenic acids (oleanic, ursolic, crataegolic), biogenic amines (ethylamine, acetylcholine, phenethylamine), and organic acids (chlorogenic and caffeic acids).