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 is a minor problem for most agricultural crops, since it is not a competitive species, being intolerant of shade from other plants and unable to survive tilling. It also hosts many insects, some of which can be harmful to other plants. Although individuals are easy to remove by hand, populations are difficult to eliminate permanently.
Although commonly used in traditional medicine, no approved drugs are made from this plant. It has been used to make dyes and torches.
Description
V. thapsus is a dicotyledonous plant that produces a rosette of leaves in its first year of growth.Blamey, M., & Grey-Wilson, C. (1989). Flora of Britain and Northern Europe. Hodder & Stoughton, . 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 that can occupy up to half the stem length. All parts of the plants are covered with star-shaped trichomes. This cover is particularly thick on the leaves, giving them a silvery appearance. The species' chromosome number is 2n = 36.
On flowering plants, the leaves are alternately arranged up the stem. They are thick and decurrent, with much variation in leaf shape between the upper and lower leaves on the stem, ranging from oblong to oblanceolate, and reaching sizes up to 50 cm long and 14 cm across (19 inches long and 5 inches wide).Huxley, A., ed. (1992). New RHS Dictionary of Gardening. Macmillan. They become smaller higher up the stem, and less strongly decurrent down the stem. The flowering stem is solid and 2–2.5 cm (nearly an inch) across, and occasionally branched just below the inflorescence, usually following damage. After flowering and seed release, the stem and fruits usually persist in winter, drying into dark brown, stiff structures of densely packed, ovoid-shaped, and dry seed capsules. The dried stems may persist into the following spring or even the next summer. The plant produces a shallow taproot.
Flowers are pentamerous with (usually) five stamen, a five-lobed calyx tube, and a five-petalled corolla, the latter bright yellow and wide. The flowers are almost sessile, with very short pedicels (2 mm, 0.08 in). The five stamens are of two types, with the three upper stamens being shorter, their filaments covered by yellow or whitish hairs, and having smaller anthers, while the lower two stamens have glabrous filaments and larger anthers.They are all hairy in subspecies V. crassifolium and V. giganteum. 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) in size, marked with longitudinal ridges. A white-flowered form, V. thapsus f. candicans, is known to occur. Flowering lasts up to three months from early to late summer (June to August in northern Europe), with flowering starting at the bottom of the spike and progressing irregularly upward; each flower opens for part of a day and only a few open at the same time around the stem.
Taxonomy For the purpose of botanical nomenclature, Verbascum thapsus was first described by Carl Linnaeus in his 1753 . The specific epithet thapsus had been first used by Theophrastus (as , ) for an unspecified herb from the Ancient Greek settlement of Thapsos, near modern Syracuse, Sicily, Den virtuella Floran: Verbascum thapsus , retrieved on 6 November 2009. 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, which has led to the plant acquiring many synonyms over the years. Introduced American populations show much less variation.
The taxonomy of Verbascum has not undergone any significant revision since Svanve Mürbeck's monographs in the 1930s, with the exception of the work of Arthur Huber-Morath, who used informal grouping in organizing the genus for the florae of Iran and Turkey to account for many intermediate species. Since Huber-Morath's groups are not taxonomical, Mürbeck's treatment is the most current one available, as no study has yet sought to apply genetic or molecular data extensively to the genus. In Mürbeck's classification, V. thapsus is placed in sect. Bothrospermae subsect. Fasciculata alongside species such as Verbascum nigrum (black or dark mullein), Verbascum lychnitis (white mullein), and Verbascum sinuatum (wavy-leaved mullein). As Verbascum thapsus is the type species of the genus the application of article 22 of the ICNafp gives sect. Verbascum subsect. Verbascum as the correct nomenclature for this placement.
Subspecies and hybrids
+ Hybrids of Verbascum thapsusHybrid nameOtherparent speciesNotesV. × duernsteinense TeyberV. speciosumV. × godronii BoreauV. pulverulentumV. × kerneri FritschV. phlomoidesV. × lemaitrei BoreauV. virgatumV. × pterocaulon Franch.V. blattariaV. × thapsi L.V. lychnitissyn. V. × spurium W.D.J.Koch, may be anomen ambiguumV. × semialbum Chaub. V. nigrumnoneV. pyramidatum 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. (syn. subsp. montanum (Scrad.) Bonnier & Layens) V. t. giganteum (Willk.) Nyman; Spain, endemic. In all subspecies but the type, the lower stamens are also hairy. 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. Both V. t. giganteum and V. t. crassifolium were originally described as species. Due to its morphological variation, V. thapsus has had a great many subspecies described. A recent revision led its author to maintain V. giganteum but sink V. crassifolium into synonymy.
The plant is also parent to several hybrids (see table). Of these, the most common is V. × semialbum Chaub. (× V. nigrum). All occur in Eurasia, and three, V. × kerneri Fritsch, V. × pterocaulon Franch. and V. × thapsi L. (syn. V. × spurium W.D.J.Koch), have also been reported in North America.
Common names V. thapsus is known by a variety of names. European reference books call it "great mullein".Watts (2000), pp. 633–634. 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: “lamb’s ear”, "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",Watts (2000), pp. 108, 369. 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".Watts (2000), pp. 774–775, 819–820. p. 866: "A tall plant like Mullein attracts 'staff' and 'rod' names." The name "velvet dock" or "mullein dock" is also recorded, where "dock" is a British name applied to any broad-leaved plant.Watts (2000), pp. 302, 634.
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.Flora Europaea: Verbascum thapsus , retrieved on 6 November 2009. In northern Europe, it grows from sea level up to 1,850 m altitude, while in China it grows at 1,400–3,200 m altitude.
It has been introduced throughout the temperate world, and is established as a weed in Australia, New Zealand, tropical Asia, La Réunion, North America, Hawaii, Chile, Hispaniola, and Argentina. It has also been reported in Japan.
In the United States, it was imported very early in the 18th century and cultivated for its medicinal and piscicide properties. By 1818, it had begun spreading so much that Amos Eaton thought it was a native plant. 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.[], retrieved 29 December 2006.
Great mullein most frequently grows as a colonist of bare and disturbed soil, usually on sandy or chalky ones. It grows best in dry, sandy, or gravelly soils, although it can grow in a variety of habitats, including banksides, meadows, roadsides, forest clearings, and pastures. This ability to grow in a wide range of habitats has been linked to strong phenotype variation rather than adaptation capacities.
Ecology
Great mullein is a biennial and generally requires winter dormancy before it can flower. This dormancy is linked to starch degradation activated by low temperatures in the root, and gibberellin application bypasses this requirement. Seeds germinate almost solely in bare soil, at temperatures between 10 and 40 °C. While they can germinate in total darkness if proper conditions are present (tests give a 35% germination rate under ideal conditions), in the wild, they in practice only do so when exposed to light, or very close to the soil surface, which explains the plant's habitat preferences. While it can also grow in areas where some vegetation already exists, growth of the rosettes on bare soil is four to seven times more rapid.