Verbascum thapus is one of at least 250 species in the genus. It is a strong-growing hardy biennial herb that presents with alternating leaves and long terminal spikes of mostly yellow flowers. This species is also know as Great Mullein or Aaron’s rod and grows tall, up to a height of 78 inches with grayish, downy or woolly basal leaves. Between July and September, the plants bloom with club-shaped spikes of yellow flowers (Le Strange 1977).
Native to Europe and Asia, but now widely naturalized in North America, V. thapsus was used in during the Roman era to make various products. They include oil wicks from the dried whitish down of the plant, hair dyes from the flowers mixed with lye, or fish narcotics derived from crushed seeds to make stealing from private ponds easier. The medicinal uses for the plant weren’t overlooked at the time either. Dioscorides administered the roots for diseases of the lungs, while Pliny gave its leaves to broken-winded horses (Le Strange 1997). Up to and beyond the medieval period, the plant was widely prescribed throughout Europe as decoction for chest pains, “wasting diseases, coughing, spitting of blood, consumption, laxes, fluxes, convulsions, and cramps” (Le Strange 1997).
Current Medicinal Uses
Mullein preparations remain popular in oils, alcohol extracts, capsules, or as dried leaves and flowers (Turker 2005). Uses of the plant include poultices to treat hemorrhoids, homeopathic tinctures to treat migraines, and mullein oil as a bactericide (Grieve 1931). Given the level of use outside of conventional medicine and the presence of rotenone and coumarins in the plant, researchers in recent years have began to focus more light on studying the chemical properties present in wild mullein (Turker 2005).
Hairs on the plant leaves can act as an irritant (Foster 1990). No cases of toxicity were identified. However given the composition of the plant, care should be taken (Foster 1990).
Foster. S. & Duke. J. A. A Field Guide to Medicinal Plants. Eastern and Central N. America. Houghton Mifflin Co. 1990.
Grieve M. A Modern Herbal. Tiger Books International, London, 1998 (first published in 1931 by Jonathan Cape Ltd).
Le Strange, R. A History of Herbal Plants. Arco Publishing Company, Inc., New York, 1977.
Turker, AU. Common mullein (Verbascum thapsus L.): recent advances in research. Phytother Res. 2005 Sep;19(9):733-9.
USDA. http://plants.usda.gov (Accessed July 21, 2009) Search term: Verbascum thapsus