The Mulleins (Verbascum) are a genus of about 250 species of flowering plants in the figwort family (Scrophulariaceae). They are native to Europe and Asia, with the highest species diversity in the Mediterranean region.
They are biennial or perennial plants, rarely annuals or subshrubs, growing to 0.5-3 m tall. The plants first form a dense rosette of leaves at ground level, subsequently sending up a tall flowering stem. The leaves are spirally arranged, often densely hairy, though glabrous (hairless) in some species. The flowers have five symmetrical petals; petal colours in different species include yellow (most common), orange, red-brown, purple, blue or white. The fruit is a capsule containing numerous minute seeds.
The entire plant contains coumarin and rotenone, with the highest concentrations of these compounds present in the plants seeds. The plant has a long history of use as a medicine, and is an effective treatment for asthma and respiratory disorders. Extracts made from the plants flowers are a very effective treatment for ear infections. Although this plant is a recent arrival to North America, Native Americans used the ground seeds of this plant as a paralytic fish poison due to their high levels of rotenone. The seeds of this plant should not be consumed and can cause internal hemmoraging if ingested. The high coumarin content of the seeds makes the plant an effective blood thinner. Coumarin is the primary ingredient used in rat poisons. Ingestion of rotenone has been linked as a causative agent of Parkinson's disease.
Since the year 2000 a number of new hybrid cultivars have come out that have increased flower size with shorter heights and tend to be longer lived plants. A number have new colors for this genus. Many are raised from seed, both the short lived perennial and biennial types. In the landscape they are valued for their tall narrow stature and for flowering over a long period of time, even in dry soils.
Mullein is also the active ingredient in many alternative smoking blends.