Moth mullein is a biennial forb that is native to Europe. The seed is a round capsule about 8.5 mm in diameter. Upon maturity, it splits into 2 cells filled with seeds that are dark brown. The surface of the seeds is marked with many ridges and grooves. The cotyledons are spatula-shaped. The flowers occur on the ends of erect stems that are produced during the second year of growth. The flowers are yellow to white in color with 5 petals that have purple centers and are 2 to 3 cm in diameter. Leaves initially develop as a basal rosette. Leaves in the first year of growth are oval in outline with slightly wavy margins. In the second year of growth, they alternate along the flowering stem. Mature leaves are not hairy, oblong in shape, and have toothed margins. They are also 8 to 45 cm long and 3 to 15 cm wide. Stems are erect and stout reaching 0.61 to 1.5 m tall.