Damiana leaves come from a small shrub that’s found throughout Mexico, Central America and the West Indies, as well as parts of South America. This shrub has pale yellow flowers that bloom in early to late summer. However, the most important part of the plant is its leaves, which are harvested during the flowering season. The leaves contain essential oil, resins, tannins, starch, arbutin, bartering and a bitter substance known as damianin.