Mullein

This week’s Weed – Mullein

ChiloquinNews article August 6th, 2012

mature Verbascum thapsus plants

mature Verbascum thapsus plants

The mulleins, genus Verbascum are a genus of about of 250 species in the figwort family, native to Europe and Asia. In the garden Verbascums are valued for their tall flower spikes. There are a number of new hybrid cultivars that are not at all invasive. Common mullein (Verbascum thapsus) is a different story, although it is still an impressive plant. I have sometimes allowed the huge downy-leaves rosettes to grow, but believe me, if you let it flower and set seed you will be sorry.

Common mullein was first introduced into the U.S. in the mid-1700’s, where it was used as a piscicide, or fish poison, in Virginia (the seeds contain several compounds – saponins, glycosides, coumarin, rotenone – that cause breathing problems in fish).  It quickly spread throughout the U.S. Records show that it was first described in Michigan in 1839 and on the Pacific coast in 1876 probably from of multiple introductions by settlers because of its myriad uses.

Mullein has been used since ancient times as a remedy for skin, throat and breathing ailments and it is now widely available in health and herbal stores in herbal remedies with emollient and astringent properties. It is the active ingredient in many alternative smoking blends. Dried flowers are used in herbal teas, but all preparations meant to be drunk have to be finely filtered to eliminate the irritating hairs. Oil from the flowers was used against catarrhs, colics and, in Germany, earaches, frostbite, eczema and other external conditions. The flowers provide dyes of bright yellow or green, and have been used for hair dye. The dried leaves and hair were made into candle wicks, or put into shoes to help with insulating them. The dried stems were also dipped into suet or wax to make torches. It is considered a first-rate drill for use in the hand drill method of friction fire lighting. A methanol extract from common mullein has been used as an insecticide for mosquito larvae.

Common mullein is intolerant of shade, but will grow in almost any open area, and threatens natural meadows and forest openings, where it adapts easily to a wide variety of conditions. Once seeds have germinated, it grows more vigorously than most native plants, and it can overtake a site in fairly short order.  It is a prolific seeder and its seeds last a very long time in the soil.  An established population can be extremely difficult to eradicate. It is a very minor problem for most agricultural crops, since it is not a very competitive species, being intolerant of shade and unable to survive tilling. Except in areas where vegetation is sparse to begin with, such as eastern California and Oregon, it rarely becomes aggressively invasive, since its seed require open ground to germinate, and mullein rarely establishes on new grounds without human intervention because its seeds do not disperse very far. Despite not being an agricultural weed in itself, it hosts a number of insects and diseases, including both pests and beneficial insects. A study found V. thapsus hosting insects from 29 different families. Most of the pests found were western flower thrips, the tarnished plant bug, and various spider mites.

 

The first summer after the seed germinates, mullein produces a tap root and a rosette of leaves. The rosette increases in size during the growing season until low temperatures stop growth. The next spring, second year plants bolt into maturity with a flower stalk that can be up to 10 ft tall. It produces seed during the summer and then dies, completing the plant’s life cycle.  It is estimated that a single plant can produce up to 180,000 minute seeds which may remain viable for more than 100 years. Mullein plants are easily hand pulled on loose soils due to relatively shallow tap roots.  This is an extremely effective method of reducing the population if the plants are pulled before setting seeds.

Mullein seedling

Mullein seedling

The basal rosettes are spectacular.

The basal rosettes are spectacular.

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