Mullein Leaf, aka Verbascum Thapsus, is a fuzzy-leaved, herbaceous biennial in the Scrophulariaceae family. Although the plant is considered a weed that thrives in compacted, poor soils, mullein leaf has been traditionally used for its many beneficial attributes since the time of Dioscorides, over 2,000 years ago. Mullein herb can be macerated into an extract, brewed as a tea, or made into syrup.