Common and Scientific Names
- Great mullein, Aaron's rod, blanket weed
- Verbascum thapsus Linnaeus
- Family Scrophulariaceae (Foxglove and snapdragon family)
Origin and Distribution
Native to Europe and to western and central Asia, but now occurring in most temperate areas of the world. It was introduced to Australia as a garden plant and is also naturalised in Tasmania, New South Wales, Queensland, South Australia and Western Australia. It is widespread in Victoria, particularly in the Western District (mainly inland), central Victoria, the North East, Port Phillip and Westernport regions and East Gippsland.
Great mullein favours dry, well-drained sites, often in disturbed areas on hillsides. It is frequently found on shallow soils with low fertility and high pH, overlying rocks and on limestone soils, in areas with greater than 500 mm annual rainfall. Great mullein occurs on lands that were formerly cultivated, pastures, native grasslands, roadsides, railway easements, the margins of watercourses and in neglected areas.
Description and Lifecycle
An erect biennial herb 0.5 to 2.5 m high, commonly 1 to 2 m, forming a basal rosette up to 60 cm in diameter in the first year and producing a single upright flowering stem in the second year.
Stems – single, erect, densely covered with woolly white hairs. Branches from the upper leaf axils are sometimes present.
Leaves – grey-green to whitish or yellowish, densely covered with matted layers of white star-shaped hairs giving a woolly appearance and prominently veined on the underside; lower leaves, 8 to 50 cm long, 2.5 to 14 cm wide, ovate to elliptical, with a short, winged stalk and a blunt pointed apex and forming a rosette close to the ground; stem leaves to 30 cm long, becoming smaller up the stem, stalkless, with a winged extension onto the stem.
Flowers – November to March; yellow, 15 to 30 mm in diameter, 12-18 mm long, densely arranged in groups of 2 to 7 on 1 to 5 mm long stalks in the axils of small bracts off the upright spike, and totalling up to several hundred per spike; 5 fused petals, 5 sepals, 5 stamens. The sepals are 6 to 12 mm long and the corolla (joined petals) is hairy on the outside. The upper 3 stamens have short, white, woolly filaments, the lower 2 have longer, hairless filaments. The lowest flowers on the stem mature first.
Fruit - an ovoid to globose, hairy capsule, 7 to 10 mm long, with a short stalk. Green when young, brown when dry, splitting into 2 valves when mature.
Seeds – up to 600 per capsule, reddish brown, pitted and ridged, less than 1 mm long, 5 or 6 sided, rod-shaped with one pointed end.
Roots – long, stout taproot. Great mullein is mainly a biennial but can become a short-lived perennial. Seeds germinate in spring and autumn and seedlings develop to form a large rosette by summer. Flowering mainly occurs from January to March. The flowers open in the early morning and close by mid-afternoon. They self-pollinate if cross-pollination does not occur. Plants die in autumn but the dry stems can remain standing for several months.
Similar speciesThere are three other Verbascum species in Victoria, all introduced. Verbascum virgatum, twiggy mullein, is less robust than great mullein, has leaves that are more elongate, are dark green, with scalloped margins and lack the dense covering of soft whitish hairs. The stalks of the flowers and seed pods are usually 2 to 5 mm long. It is a common weed in much of Victoria south of Echuca and Horsham. V. blattaria, moth mullein, also has green leaves that lack hairs or are sparsely hairy but has basal leaves that are lobed or toothed and flowers on stalks 10 to 25 mm long. It is locally common in the North East and uncommon in other parts of southern and eastern Victoria. Unlike the other three naturalised Verbascum species, V. creticum, Cretan mullein, has serrated bracts and sepals, and only 4 stamens, and is known from few widely scattered localities mainly in southern Victoria.
Great mullein is suspected of being poisonous, but in pastures is rarely eaten by livestock. Seeds have long term viability and have been claimed to survive in soil for several hundred years.
Numerous medicinal properties have been attributed to the plant which has provided various traditional folk remedies and treatments. The petals and stamens are collected for use in medicine. The leaves have been used as lamp wicks, insoles for footwear and a source of mucilage for smoking. The flowers have provided a source of yellow dye.
The seeds have no special adaptation for dispersal but can contaminate a wide range of materials. They mainly fall within a short distance of the plant.
Prescribed measures for the control of noxious weeds
- Application of a registered herbicide
- Physical removal
Important information about prescribed measures for the control of noxious weeds.
Other management techniques
Changes in land use practices and spread prevention may also support great mullein management after implementing the prescribed measures above.
No biological control agents are available or under development for this weed in Australia. The European weevil Gymnaetron tetrum, accidentally introduced to the USA, causes extensive seed destruction in some areas.
- Contact your local landcare or friends group for further assistance and advice.
- Call the DEPI Customer Service Centre on 136 186.
- Weeds Australia (external link)
Barker, W.R. and Harden, G.J. (1999) Verbascum. Pp. 498-500 in N.G. Walsh and T.J. Entwisle (Eds.) Flora of Victoria Volume 4. Dicotyledons Cornaceae to Asteraceae. Melbourne, Inkata Press.
Parsons, W.T. and Cuthbertson, E.G. (1992) Noxious Weeds of Australia. Melbourne, Inkata Press.
This Information Note was developed by The Department of Primary Industry.
Compiled by Ian Faithfull. Edited by Jack Craw. Image processing Les Bould. Figure1 by H. tanislawska. Updated by Melanie Martin, DPI, October 2006. Chemical information supplied by Chemical Standards Branch, August 2006. Updated by Greg Johnson, DPI, September 2007.