Verbascum thapsus, the great mullein, greater mullein or common mullein, is a species of mullein native to Europe, northern Africa, and Asia, and introduced in the Americas, Australia and New Zealand.
It is a hairy biennial plant that can grow to 2 m tall or more. Its small, yellow flowers are densely grouped on a tall stem, which grows from a large rosette of leaves. It grows in a wide variety of habitats, but prefers well-lit, disturbed soils, where it can appear soon after the ground receives light, from long-lived seeds that persist in the soil seed bank. It is a common weedy plant that spreads by prolifically producing seeds, and has become invasive in temperate world regions. It has been used to make dyes and torches. The leaves are large, up to 50 cm long. The second-year plants normally produce a single unbranched stem, usually 1–2 m tall. In the eastern part of its range in China, it is, however, only reported to grow up to 1.5 m tall. The tall, pole-like stems end in a dense spike of flowers This cover is particularly thick on the leaves, giving them a silvery appearance. The species' chromosome number is 2n = 36. After flowering and seed release, the stem and fruits usually persist in winter, The plant produces small, ovoid (6 mm, 0.24 in) capsules that split open by way of two valves, each capsule containing large numbers of minute, brown seeds less than 1 mm (0.04 in) though it is often assimilated to the ancient Tunisian city of Thapsus.
At the time, no type specimen was specified, as the practice only arose later, in the 19th century. When a lectotype (type selected amongst original material) was designated, it was assigned to specimen 242.1 of Linnaeus' herbarium, the only V. thapsus specimen. The species had previously been designated as type species for Verbascum. European plants exhibit considerable phenotypical variation, Introduced American populations show much less variation.
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!Hybrid name
!Other<br />parent species
!Notes
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|V. × duernsteinense Teyber
|V. speciosum
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|V. × godronii Boreau
|V. pulverulentum
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|V. × kerneri Fritsch
|V. phlomoides
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|V. × lemaitrei Boreau
|V. virgatum
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|V. × pterocaulon Franch.
|V. blattaria
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|V. × thapsi L.
|V. lychnitis
|syn. V. × spurium<br /> W.D.J.Koch, may be a<br />nomen ambiguum
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|V. × semialbum Chaub.
|V. nigrum
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|none
|V. pyramidatum
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The three usually recognized subspecies are:
- V. t. thapsus; type, widespread.
- V. t. crassifolium (Lam.) Murb.; Mediterranean region and to 2000 metres in southwestern Austria. In V. t. crassifolium, the hairiness is less dense and often absent from the upper part of the anthers, while lower leaves are hardly decurrent and have longer petioles. In V. t. giganteum, the hairs are densely white tomentose, and lower leaves are strongly decurrent. V. t. crassifolium also differs from the type in having slightly larger flowers, which measure 15–30 mm wide, whereas in the type, they are 12–20 mm in diameter.
The plant is also parent to several hybrids (see table). Of these, the most common is V. × semialbum Chaub. (× V. nigrum).
Common names
V. thapsus is known by a variety of names. European reference books call it "great mullein". In North America, "common mullein" is used while western United States residents sometimes refer to mullein as "cowboy toilet paper".
In the 19th century, it had well over 40 different common names in English alone. Some of the more whimsical ones included "hig candlewick", "Indian rag weed", "bullicks lungwort", "Adams-rod", "hare's-beard", and "ice-leaf". Vernacular names include innumerable references to the plant's hairiness: "woolly mullein", "velvet mullein", or "blanket mullein", "beggar's blanket", "Moses' blanket", "poor man's blanket", "Our Lady's blanket", or "old man's blanket", and "feltwort", and so on ("flannel" is another common generic name). "Mullein" itself derives from the French word for "soft".
Some names refer to the plant's size and shape: "shepherd's club(s)" or "staff", "Aaron's rod" (a name it shares with a number of other plants with tall, yellow inflorescences), and a plethora of other "X's staff" and "X's rod". The name "velvet dock" or "mullein dock" is also recorded, where "dock" is a British name applied to any broad-leaved plant.
Alongside Aaron's rod, Verbascum thapsus is sometimes referred to as Aaron's beard, a name it shares with several other plants.
Distribution and habitat
V. thapsus has a wide native range including Europe, northern Africa, and Asia, from the Azores and Canary Islands east to western China, north to the British Isles, Scandinavia, and Siberia, Kashmir and south to the Himalayas. In northern Europe, it grows from sea level up to 1,850 m altitude, It has also been reported in Japan.
In the United States, it was imported very early in the 18th In 1839, it was already reported in Michigan and in 1876, in California. It is now found commonly in all the states. In Canada, it is most common in the Maritime Provinces and southern Quebec, Ontario, and British Columbia, with scattered populations in between.
Great mullein most frequently grows as a colonist of bare and disturbed soil, usually on sandy or chalky ones.
Ecology
thumb|left|upright|alt=A Mullein plant growing in aa dry, mountainous area.|V. thapsus grows best with little competition.
Great mullein is a biennial and generally requires winter dormancy before it can flower. Triennial individuals have been found to produce fewer seeds than biennial and annual ones. While year of flowering and size are linked to the environment, most other characteristics appear to be genetic.
A given flower is open only for a single day, opening before dawn and closing in the afternoon. The hair on lower stamens may serve to provide footholds for visitors. Because of this, and because the plant is an extremely prolific seed bearer (each plant produces hundreds of capsules, each containing up to 700 seeds, The seeds are generally too small for birds to feed on, Other bird species have been reported to consume the leaves (Hawaiian goose) or flowers (palila), or to use the plant as a source when foraging for insects (white-headed woodpecker). Additionally, deer and elk eat the leaves.
Fossil record
Seeds of V. thapsus have been recorded from part of the Cromer Forest Bed series and at West Wittering in Sussex from some parts of the Ipswichian interglacial layers.
Agricultural impacts and control
Because it cannot compete with established plants, great mullein is no longer considered a serious agricultural weed and is easily crowded out in cultivation, except in areas where vegetation is sparse to begin with, such as Californian semidesertic areas of the eastern Sierra Nevada in the USA. In such ecological contexts, it crowds out native herbs and grasses; its tendency to appear after forest fires also disturbs the normal ecological succession. The species is legally listed as a noxious weed in the US state of Colorado (class C) and Hawaii, and the Australian state of Victoria (regionally prohibited in the West Gippsland region, and regionally controlled in several others).
Despite not being an agricultural weed in itself, it hosts a number of insects and diseases, including both pests and beneficial insects. It is also a potential reservoir of the cucumber mosaic virus, Erysiphum cichoraceum (the cucurbit powdery mildew) and Texas root rot. A study found V. thapsus hosts insects from 29 different families. Most of the pests found were western flower thrips (Frankliniella occidentalis), Lygus species such as the tarnished plant bug (L. lineolaris), and various spider mites from the family Tetranychidae. These make the plant a potential reservoir for overwintering pests. The plant's ability to host both pests and beneficials makes it potentially useful to maintain stable populations of insects used for biological control in other cultures, like Campylomma verbasci and Dicyphus hesperus (Miridae), a predator of whiteflies. A number of pest Lepidoptera species, including the stalk borer (Papaipema nebris) and gray hairstreak (Strymon melinus), also use V. thapsus as a host plant.
thumb|upright|alt=A series of leaves is seen wrapping down the length of a stem. The leaves have thick veining and both they and the stem have a woolly appearance from the hair covering them.|Because of ample irritating hair, V. thapsus is resistant to grazing and contact herbicides.
Control of the plant, when desired, is best managed via mechanical means, such as hand pulling and hoeing, preferably followed by sowing of native plants. Animals rarely graze it because of its irritating hairs, and liquid herbicides require surfactants to be effective, as the hair causes water to roll off the plant, much like the lotus effect. Burning is ultimately ineffective, as it only creates new bare areas for seedlings to occupy.
Traditional medicine
thumb|"Verbasci flos": dried flowers of V. thapsus as used in herbal tea
Although long used in herbal medicine, no drugs are manufactured from its components. Leaves were smoked to attempt to treat lung ailments, a tradition that in America was rapidly transmitted to Native American peoples. The Zuni people, however, use the plant in poultices of powdered root applied to sores, rashes, and skin infections. An infusion of the root is also used to treat athlete's foot. 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, earaches, frostbite, eczema, and other external conditions. boils, carbuncles, hemorrhoids, and chilblains, amongst others. The German Commission E describes uses of the plant for respiratory infections. It was also part of the National Formulary in the United States Native Americans and American colonists lined their shoes with leaves from the plant to keep out the cold.|group=note great mullein was linked to witches,
Due to its weedy capacities, the plant, unlike other species of the genus (such as V. phoeniceum), is not often cultivated.