Common Mullein

Verbascum thapsus

Keys to Identification

  • Flowers are yellow, saucer-shaped, attached to the stem
  • Leaves are oblong and woolly with a rounded tip
  • Stems are erect, rigid, up to 6 feet tall, covered with woolly hairs

Family

Scrophulariaceae – Figwort Family

Other Names

Flannel plant, velvet dock, woolly mullein, Jupiter’s staff

USDA Code

VETH

Legal Status

Colorado Noxious Weed List C

Identification

Lifecycle

Biennial.  First year plants are a basal rosette of oblong leaves covered with woolly hairs. The plant bolts in the second year and then dies after flowering

Growth form

Forb/herb

Flower

Flowers are five-petaled and yellow. Grow in terminal spikes that can be 20+ inches long. Flowering June through August

Seeds/Fruit

The fruit is an ovoid capsule that splits  

Leaves

Basal rosette of woolly leaves the first year followed by woolly stem leaves the second year. Stem leaves alternate, somewhat clasping, and decrease in size towards the end of the stem

Stems

Thick, erect, nearly leafless.  Two to six feet tall

Roots

Thick taproot

Seedling

Basal rosette of hairy, broad, oblong leaves.  Leaves have a long petiole and entire margins

Similar Species

Exotics

Lamb’s ears (Stachys byzantina).
Moth mullein (Verbascum blattaria) Colorado noxious weed, List B

Natives

Miner’s candle (Cryptantha virgata)
Green gentian (Fraser speciosa)

Impacts

Agricultural

Rarely eaten by animals. May form large patches that reduce grazing. Does not survive tilling

Ecological

Once established it grows quickly to form a dense ground cover. It will overtake and displace native species. At high densities, it may prevent establishment of native herbs and grasses following fires or other disturbances.

Found in neglected meadows, forest openings, pastures, fence rows, roadsides, and industrial areas

Human

Leaf hairs may irritate human skin. May affect some recreational activities and impose a negative visual effect on cultural sites

Habitat and Distribution

General requirements

Occurs in areas with an average annual precipitation of 20-60 in. (0.5-1.5 m) and a 140-day growing season. Prefers well-drained soils with pH 6.5 to 7.8. Prefers dry sandy soils but can grow in chalk and limestone.  Found in meadows, prairies, desert shrublands, chaparral, deciduous woodlands, and coniferous forests 

Distribution

Found in all US states and throughout most of North America. Within the contiguous US, common mullein is often described widespread, conspicuous, or everywhere. In much of the US, common mullein as considered adventive or naturalized

Historical

Native to Europe and Asia.  First noted in NA in the mid-1700’s

Biology/Ecology

Life cycle

Biennial.  The first year rosette undergoes vernalization in the fall/winter.  Vernalization is required to induce flowering the following spring

Mode of reproduction

Seed

Seed production

Mature plants can produce up to 100,000 or more per plant

Seed bank

Seeds may last 100+ years in the soil

Dispersal

Seeds drop to the ground, usually within a few feet of the plant

References

Colorado Department of Agriculture – Common mullein fact sheet – https://www.colorado.gov/pacific/agconservation/common-mullein

BugwoodWiki –  https://wiki.bugwood.org/Verbascum_thapsus#Description

Forb Seedling Identification Guide, NRCS, Pullman Plant Materials Center. P.138.            Authors: Pamela Pavek, USDA NRCS; Brenda Erhardt, Latah Soil and Water Conservation District; Trish Heekin, Latah Soil and Water Conservation District; Richard Old, XIS Services, Inc.

Invasive Plant Atlas of the United States – https://www.invasiveplantatlas.org/subject.html?sub=3080

USDA-USFS Fire Effects Information System (FEIS). “Verbascum Thapsus” –  https://www.feis-crs.org/feis/

Invasive.org – https://www.invasive.org/weedcd/pdfs/wgw/commonmullein.pdf

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Common mulleinCommon mullein rosetteCommon mullein patchCommon mullein stalk