Verbascum thapsus
(common mullein)

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Identity

Preferred Scientific Name

• Verbascum thapsus L.

Preferred Common Name

• common mullein

Other Scientific Names

• Leiosandra cuspidata Raf.
• Thapsus linnaei Opiz.
• Thapsus schraderi Opiz.
• Verbascum lanatum Gilib.
• Verbascum simplex Hoffmanns. & Link

International Common Names

• English: Aaron's-rod; big taper; blanketweed; common mullein; common mullein; cowboy toilet paper; flannel mullein; flannel plant; flannelleaf; great mullein; great mullein; grey mullein; hag taper; mullein; torches; velvet dock; velvet plant; wild tobacco; wooley mullein; woolly mullein
• Spanish: gordolobo común; gordolobo común; guardalobo; hierba del Paño
• French: bonhomme; bouillon blanc; bouillon blanc à petites fleurs; bouillon-blanc; grande molène; molène; molène bouillon-blanc; molène vulgaire
• Russian: korovâk obyknovennyj
• Chinese: mao rui hua
• Portuguese: barbaco

Local Common Names

• Germany: Kleinbluetige Koenigskerze; Kleinblütige Königskerze
• Italy: barbasco maschio; tasso barbasso
• Japan: birodomozuika; birodo-mozuika; niwatabako
• Netherlands: koningskaars; koningskaars
• Portugal: barbasco; verbasco
• Sweden: kungsljus; vanligt kungsljus

EPPO code

• VESTH (Verbascum thapsus)

Summary of Invasiveness

V. thapsus is a biennial herb native to Europe, north Africa and western and central Asia. It has become naturalized in most temperate regions of the world, where it can be locally abundant on roadsides, railroads, fence rows, old fields, pastures and other open, disturbed areas (PIER, 2014; USDA-NRCS, 2014). Once established, it exhibits vigorous growth and threatens native plants in meadows and forest gaps. Each individual can produce 100,000-175,000 seeds that can remain viable for more than 100 years, making established populations of V. thapsus difficult to eradicate (Gross and Werner, 1982; ISSG, 2014).

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Scrophulariales
•                         Family: Scrophulariaceae
•                             Genus: Verbascum
•                                 Species: Verbascum thapsus

Notes on Taxonomy and Nomenclature

Verbascum thapsus (L.) is a member of the Scrophulariaceae family of angiosperms. Native to Asia and Europe, Verbascum is a now widespread genus in this family, with about 250 species. The genus name and several of the many common names for V. thapsus refer to the dense wooly hairs that cover the surface of its leaves. The soft leaves also give rise to regional names such as ‘cowboy toilet paper’. Other common names are based on the tall flowering stem that is produced in its second year.

Linnaeus first published the name Verbascum thapsus in 1753. The genus name Verbascum was derived from the old Latin name for the species, barbascum, which means ‘bearded plant’. Thapsus was a city in what is now Tunisia. The common name, mullein, is derived from the Latin word mollis, which means ‘smooth or with soft hairs’ (OSU, 2003; Charters, 2015).

This species has three accepted subspecies: V. thapsus subsp. thapsus L.; V. thapsus subsp. crassifolium (DC.) Murb.; and V. thapsus subsp. giganteum (Willk.) Nyman (The Plant List, 2013). However, a number of other sub-taxa have been proposed and may be present in the literature: V. thapsus var. thapsus; V. thapsus f. thapsus; V. thapsus f. candicans House; V. thapsus subsp. thapsus L.; V. thapsus subsp. langei Rivas Mart.; V. thapsus subsp. litigiosum (Samp.) A.Galán and Vicente Orell.; V. thapsus subsp. martinezii (Valdés) A.Galán and Vicente Orell., and V. thapsus var. valentinum (Burnat and Barbey) O.Bolòs and Vigo (GBIF, 2014).

Description

From Remaley (2005), Flora of China Editorial Committee (2014), ISSG (2014) and PIER (2014):

V. thapsus is a biennial herb. During its first year, V. thapsus forms a low-growing rosette from a tap root. It has a dense yellow to white tomentose (stellate or dendritic) pubescence on the bluish grey-green leaves; blades obovate to oblanceolate, 8-50 cm by 2.5-14 cm, with margins entire to shallowly crenate.

In its second year, V. thapsus produces an erect flowering stem 30-200 cm tall. The lower stem leaves are petiolate; leaf blades oblanceolate-oblong to 15 by 6 cm with crenate margins. The other stem leaves decrease in size up the stem, with the upper stem leaves oblanceolate, sessile, and decurrent into wings on the stem.

The flowers are arranged in dense cylindrical, spicate panicles to 30 by 2 cm. The calyx of each flower is (5-) 8-12 mm long with lanceolate lobes. The corolla is yellow (rarely white), 8-15 mm long, with scurfy, stellate pubescence externally. There are five stamens. The upper three staminal filaments are villous with yellow hairs and the lower two are glabrous to sparsely villous. It produces capsules that are broadly ovoid to elliptic-ovoid, 0.7-1 cm long, and densely tomentose with stellate or branched hairs. The small seeds are pitted and rough with ridges and grooves.

Plant Type

Distribution

V. thapsus has a broad native range including Europe, north Africa and western central Asia. It has been introduced to Japan, Sri Lanka, Reunion, the Americas, Australia and New Zealand. It is naturalized in temperate regions, where it can become abundant in open, disturbed areas (PIER, 2014; USDA-NRCS, 2014).

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

V. thapsus was probably introduced to North America several times as a medicinal herb and by accident. In the mid-1700s, it had been introduced to Virginia for use as a piscicide (Gross and Werner, 1978). By the early 1800s, V. thapsus was so well established in North America that it was mistakenly described as a native species in an 1818 flora of the east coast. It had spread as far as Michigan by 1839 and to the Pacific coast by 1876 (Hoshovsky, 2001). It was naturalized in New Zealand by 1867 (NZPCN, 2015) and reported in Australia in the 1890s (TALA, 2015). It has also established in several Pacific Islands (PIER, 2014).

Introductions

Risk of Introduction

V. thapsus is widely available as an ornamental and is still used as a herbal remedy, so escape is a continuing threat. However, the risk of introduction and reintroduction in managed areas may be minimal; it produces many seeds, but has no specialized mechanism for dispersal. In addition, the seedlings require open, bare ground and may not establish well in late successional communities.

Habitat

In its native range, V. thapsus is commonly found on dry, rocky hillsides, disturbed areas and open woodland. It prefers dry sandy soil, but can be found in a variety of well-drained soils in meadows and forest gaps. It also grows well in open, disturbed areas such as pastures, old fields, along fence rows and roadsides, and in urban areas (Hoshovsky, 2001; ISSG, 2014).

In Hawaii, where it is introduced and invasive, it can be found in 'open sites, cinder cones, subalpine woodland and shrubland to alpine desert, 1,550-2,350 m' altitude; in New Zealand, it is found on 'poor stony or gravelly pastures, screes, stony river beds, roadsides and railways, shingle river banks and beds, dry waste places, sea level to c. 1000 m' altitude; and in Chile it grows from coastal areas up to the tree line, 2000 m altitude, particularly in dry, arid areas with 6-10 month drought periods and 100-800 mm of annual precipitation (PIER, 2014).

Habitat List

Hosts/Species Affected

Extracts from V. thapsus were reported to have some allelopathic effects on wheat seedlings, but soil cultivation practices such as ploughing usually prevent the establishment of V. thapsus in active agricultural areas (Gross and Werner, 1978).

Biology and Ecology

Genetics

The chromosome number commonly reported is 2n = 36 (30, 34) (IPCN Chromosome Reports, 2014; Missouri Botanical Garden, 2014).

Reproductive Biology

V. thapsus is cross-pollinated by short and long tongued bees, but flowers can also be autogamous. If cross-pollination has not occurred, V. thapsus will self-pollinate when the flower closes at the end of the day. It is a prolific seed bearer and a single plant may produce 100,000-175,000 seeds (Gross and Werner, 1978).

Physiology and Phenology

Seedlings are pioneer species on bare or disturbed sites. Seedling emergence and survival is limited by available light (ISSG, 2014). They emerge in early spring and form rosettes that grow into late autumn. In the second spring, the rosette forms a flowering stalk. Flowering occurs June through August, but may extend into early October. The stalk may remain erect past senescence until disturbance from wind or a large animal releases the seeds from the capsule (Gross and Werner, 1978).

Kumschick et al. (2013) found genotypes of V. thapsus from its introduced range grew larger than native genotypes under more arid conditions. Increased biomass, a strong response to increased water availability, and low root to shoot ratios suggest that V. thapsus in its introduced range exhibits a fast-growing, weedy phenotype instead of root adaption to low-water environments. Genotypes from its introduced range were also more resistant to herbivory.

In another study of invasive V. thapsus, young leaves had 6.5 times the concentration the toxic iridoid catalpol present in old leaves. This greatly reduced herbivory from generalists on young leaves, resulting in minimal losses of high-quality tissue and increased performance (Alba et al., 2013). This may help explain its success in its introduced range.

Conversely, Seipel et al. (2015) found that V. thapsus does not consistently exhibit increased performance in its invaded range. Instead, plant height, number of flowering branches and population density were more strongly influenced by local climatic differences among regions. The authors suggested that studies on this species comparing native and non-native ranges should include both plant and population characteristics from multiple regions in both ranges, as well as along environmental gradients.

Longevity

V. thapsus is biennial, rarely surviving a third (vegetative) year. Seeds can remain viable for more than 100 years in soil seed banks, and viable seeds have been found in the soil samples dated to 1300 A.D. (Gross and Werner, 1982).

Climate

Rainfall

Soil Tolerances

Soil drainage

• free

Soil reaction

• alkaline
• neutral

Soil texture

• light
• medium

Special soil tolerances

• infertile

Natural enemies

Notes on Natural Enemies

V. thapsus is susceptible to several fungi and coleopteran larvae (Gross and Werner, 1978). Powdery mildew (Erysiphe cichoracearum) and root rot (Phymatotricum omnivorum) can infect V. thapsus, but they also affect agricultural species (Hoshovsky, 2001; ISSG, 2014). The larva of the mullein moth (Cucullia verbasci) usually feeds specifically on V. thapsus, but may also feed native plant species (Hoshovsky, 2001; Remaley, 2005).

Means of Movement and Dispersal

Natural Dispersal

Seeds have no natural mechanism for long distance dispersal. The mature capsule splits and requires perturbation by wind or a large animal to release the seeds. The seeds fall near the parent plant after being released (Gross and Werner, 1978).

Accidental introduction

The plant may spread accidentally via motor vehicles and hikers along roads and trails (PIER, 2014).

Intentional Introduction

V. thapsus is dispersed by the horticulture trade as an ornamental and as a folk remedy (Remaley, 2005; ISSG, 2014).

Pathway Causes

Economic Impact

V. thapsus is listed as a noxious weed in Colorado (C list) and Hawaii (USDA-NRCS, 2014). Since cattle and sheep avoid grazing on it, V. thapsus can spread and increase the degradation of poor pastures (Gross and Werner, 1978).

Environmental Impact

V. thapsus is a prolific seed producer and each individual can produce many seeds that can remain viable for extended periods. It establishes in open disturbed areas through vigorous growth that threatens native plants diversity, especially in adjacent meadows and forest gaps (Gross and Werner, 1982; ISSG, 2014). Its large rosettes can shade out native plants (Weber, 2003). Populations of V. thapsus can be several hectares or several kilometers long, with densities up to 5.2 flowering plants/m² in disturbed areas (Gross and Werner, 1978).

Risk and Impact Factors

• Proved invasive outside its native range
• Has a broad native range
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Benefits from human association (i.e. it is a human commensal)
• Has high reproductive potential
• Has propagules that can remain viable for more than one year

• Ecosystem change/ habitat alteration
• Monoculture formation
• Reduced native biodiversity
• Threat to/ loss of native species

• Allelopathic
• Causes allergic responses
• Competition - monopolizing resources
• Competition - shading
• Rapid growth

• Highly likely to be transported internationally deliberately

Uses

Economic value

V. thapsus has some economic value as an ornamental plant in addition to several reported uses as a folk medicine. Traditionally, V. thapsus was used a remedy for coughs and diarrhoea. The leaves can have stimulatory effects when smoked (Gross and Werner, 1978). It has been reported to have several other folk medicine uses including as an anodyne, anti-inflammatory, antiseptic, antispasmodic, astringent, demulcent, diuretic, emollient, expectorant and vulnerary. Other medicinal uses under investigation include anthelmintic, antioxidant, anticancer, antimicrobial, antiviral, antihepatotoxic and anti-hyperlipidemic activity (Ali et al., 2012; Escobar et al., 2013; Morteza-Semnani et al., 2013; Riaz et al., 2013). Extracts of V. thapsus show better sedation, pre-anesthetic and anti-anxiety effects than diazepam in rats (Rezaie et al., 2012). V. thapsus has also been used as a fish poison, a dye, and to make torches and candles (Gross and Werner, 1978).

Uses List

Materials

• Dyestuffs

Medicinal, pharmaceutical

• Traditional/folklore

Ornamental

• Seed trade

Similarities to Other Species/Conditions

Verbascum blattaria (moth mullein) is similar to V. thapsus. The two plants have overlapping distributions and habits, and may hybridize (Gross and Werner, 1978). However, V. blattaria is not as robust as V. thapsus and it does not have the dense pubescence.

Prevention and Control

Physical/Mechanical Control

Small populations of V. thapsus can be removed by hand, and this is recommended in sensitive areas where other control methods may cause a greater disturbance. Often large-scale removal creates areas of bare ground that allows the establishment of new V. thapsus populations. However, normal cultivation can control the plant. Plants are best controlled during the early rosette stage when tap roots are shallow and seeds have not formed (Remaley, 2005; ISSG, 2014; PIER, 2014). For second year plants, mechanical removal before the seed capsules mature significantly reduces viable seed production and reduces changes of re-establishment (Wilbur and Hufbauer, 2012).

Cultural Control

V. thapsus seedlings are not shade tolerant and bare ground is required for emergence. Sowing invaded sites with early successional native species may decrease germination and emergence of V. thapsus seedlings. Late successional native species planted among V. thapsus invasions may also outcompete it for light and space.

Due to the dense pubescence, V. thapsus is unpalatable to cattle and sheep. However, goats will graze on it and may be useful in controlling dense infestations. It has been suggested that chickens may deplete the seed bank where mature plants have been removed (ISSG, 2014).

Biological Control

The European curculionid weevil (Gymnetron tetrum) is a seed predator specific to V. thapsus. It was introduced to North America as a biological control with some success. The larva of this beetle matures in the seed capsules and can destroy up to 50% of the seeds (Gross and Werner, 1978).

Chemical Control

Spot application of 2% glyphosate, triclopyr or tebuthiuron mixture applied to first year rosettes can control V. thapsus. However, the dense epidermal hairs can reduce the effectiveness of aqueous solutions, and a follow-up treatment at half concentration may be needed to achieve long-term control (Hoshovsky, 2001; Remaley 2005; ISSG, 2014). Broadcast foliar herbicides are effective in dense populations of V. thapsus where exposure to non-target species is minimal (Hoshovsky, 2001). Rosettes are particularly sensitive to metsulfuron (PIER, 2014).

References

Alba C; Prioreschi R; Quintero C, 2013. Population and leaf-level variation of iridoid glycosides in the invasive weed Verbascum thapsus L. Chemoecology, 23:83-92.

CHAH (Council of Heads of Australasian Herbaria), 2015. Australia's virtual herbarium. Australia: Council of Heads of Australasian Herbaria. http://avh.ala.org.au

Charters ML, 2015. California Plant Names: Latin and Greek meanings and derivations. http://www.calflora.net/

Escobar FM; Sabini MC; Zanon SM; Tonn CE; Sabini LI, 2012. Antiviral effect and mode of action of methanolic extract of Verbascum thapsus L. on pseudorabies virus (strain RC/79). Natural Product Research, 26(17):1621-1625. http://www.tandfonline.com/loi/gnpl20

Flora of China Editorial Committee, 2014. Flora of China. St. Louis, Missouri and Cambridge, Massachusetts, USA: Missouri Botanical Garden and Harvard University Herbaria. http://www.efloras.org/flora_page.aspx?flora_id=2

GBIF, 2014. GBIF data portal. Copenhagen, Denmark: Global Biodiversity Information Facility (GBIF). http://data.gbif.org

Gross KL; Werner PA, 1978. The biology of Canadian weeds. 28. Verbascum thapsus L. and V. blattaria L. Canadian Journal of Plant Science, 58(2):401-413.

Gross KL; Werner PL, 1982. Colonizing abilities of "biennial" plant species in relation to ground cover: implications for their distributions in a successional sere. Ecology, 63(4):921-931.

Hoshovsky MC, 2001. Element stewardship abstract for Verbascum thapsus. The Global Invasive Species Initiative. http://www.invasive.org/weedcd/pdfs/tncweeds/verbtha.pdf

IPCN Chromosome Reports, 2014. Index to Plant Chromosome Numbers (IPCN), Tropicos website. St. Louis, Missouri, USA: Missouri Botanical Garden. http://tropicos.org/Project/IPCN

ISSG, 2014. Global Invasive Species Database (GISD). Invasive Species Specialist Group of the IUCN Species Survival Commission. http://www.issg.org/database/welcome/

Kumschick S; Hufbauer RA; Alba C; Blumenthal DM, 2013. Evolution of fast-growing and more resistant phenotypes in introduced common mullein (Verbascum thapsus). Journal of Ecology (Oxford), 101(2):378-387. http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2745

Missouri Botanical Garden, 2014. Tropicos database. St. Louis, Missouri, USA: Missouri Botanical Garden. http://www.tropicos.org/

Morteza-Semnani K; Saeedi M; Akbarzadeh M, 2012. Chemical composition and antimicrobial activity of the essential oil of Verbascum thapsus L. Journal of Essential Oil Bearing Plants, 15:373-379.

Muhammad Riaz; Muhammad Zia-ul-Haq; Jaafar HZE, 2013. Common mullein, pharmacological and chemical aspects. Revista Brasileira de Farmacognosia, 23(6):948-959. http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-695X2013000600948&lng=en&nrm=iso&tlng=en

Niaz Ali; Shah SWA; Ismail Shah; Ghayour Ahmed; Mehreen Ghias; Imran Khan; Waqar Ali, 2012. Anthelmintic and relaxant activities of Verbascum thapsus Mullein. BMC Complementary and Alternative Medicine, 12(29):(30 March 2012). http://www.biomedcentral.com/content/pdf/1472-6882-12-29.pdf

NZPCN (New Zealand Plant Conservation Network), 2015. New Zealand Plant Conservation Network. Wellington, New Zealand: New Zealand Plant Conservation Network. http://www.nzpcn.org.nz/

Ohio State University (OSU), 2003. Ohio Perennial & Biennial Weed Guide. Ohio, USA: Ohio State University. http://www.oardc.ohio-state.edu/weedguide/

PIER, 2014. Pacific Islands Ecosystems at Risk. Honolulu, USA: HEAR, University of Hawaii. http://www.hear.org/pier/index.html

Remaley T, 2005. Common mullein (Verbascum thapsus). Plant Conservation Alliance, Alien Plant Working Group, National Park Service. http://www.nps.gov/plants/alien/fact/veth1.htm

Rezaie A; Ebrahimi M; Issabeagloo E; Kumar M; Nazeri M; Rezaie S; Zakhireh S, 2012. Study of sedative, pre-anesthetic, and anti-anxiety effects of Verbascum thapsus L. extract compared with diazepam in rats. Advances in Bio Research, 3(4):84-89. http://www.soeagra.com/abr/abrdec_2012/14.pdf

Seipel T; Alexander JM; Daehler CC; Rew LJ; Edwards PJ; Dar PA; McDougall K; Naylor B; Parks C; Pollnac FW; Reshi ZA; Schroder M; Kueffer C, 2015. Performance of the herb Verbascum thapsus along environmental gradients in its native and non-native ranges. Journal of Biogeography, 42(1):132-143. http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2699

TALA, 2015. The Atlas of Living Australia. Canberra, Australia: ALA. http://www.ala.org.au/

The Plant List, 2013. The Plant List: a working list of all plant species. Version 1.1. London, UK: Royal Botanic Gardens, Kew. http://www.theplantlist.org

USDA-ARS, 2014. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx

USDA-NRCS, 2014. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/

Weber E, 2003. Invasive plant species of the world: A reference guide to environmental weeds. Wallingford, UK: CAB International, 548 pp.

Wilbur HD; Hufbauer RA, 2012. Timing control efforts to limit seed set of common mullein (Verbascum thapsus). Invasive Plant Science and Management, 5(3):390-394. http://wssajournals.org/loi/ipsm

Links to Websites

Contributors

30/03/15 Original text by:

Jeff Masters, University of Louisville, USA

Distribution Maps