Family: Scrophulariaceae

Origin, Description & Uses
Verbascum virgatum (twiggy mullein or wand mullein) is a biennial herb native to Europe that has become established in many temperate regions of the world, including Hawaiʻi. It forms a basal rosette of soft, fuzzy leaves during its first year, followed by one or more tall, slender flowering stalks that can reach over 6 feet (2 m) tall. The stalks bear numerous pale yellow flowers over an extended blooming period, making the plant attractive in cottage gardens and naturalistic landscapes. Although it has occasionally been grown as an ornamental and has a limited history of traditional medicinal use similar to other mulleins, it is not widely cultivated for economic purposes.

Risks & Threats
Verbascum virgatum is naturalized on Hawaiʻi Island and elsewhere and possesses traits that are cause for concern. It produces abundant long-lived seeds that can remain viable in the soil for many years, allowing populations to persist and rapidly colonize disturbed sites, roadsides, pastures, and open natural areas. Once established, dense stands can compete with native and desirable vegetation, making restoration more difficult and increasing management costs. Its ability to spread into open habitats means it could detrimentally impact tropical island ecosystems if left unmanaged. Whenever possible, choose a low-risk or native alternative for landscaping and restoration projects. Because this species is already established in parts of Hawaiʻi, existing populations should be managed and new plantings avoided—particularly in areas where it is not yet widespread—to help minimize further spread and ecological impacts.

High Risk Traits:

• Elevation range exceeds 1000 m, demonstrating environmental versatility
  
• Naturalized on Hawaii Island and elsewhere
  
• A disturbance-adapted environmental weed
  
• Other Verbascum species (e.g. V. thapsus) are invasive
  
• Potentially allelopathic
  
• Low palatability may give plants a competitive edge over more preferred browse species
  
• Forms dense cover that can exclude other vegetation
  
• Tolerates many soil types
  
• Reproduces by seeds
  
• As a biennial, reaches maturity in 2 years
  
• Small seeds dispersed by wind, stuck to vehicles, equipment, mud, and animals
  
• Prolific seed production (numbers unspecified)

Low Risk Traits:

• Unarmed (no spines, thorns or burrs)
  
• Ornamental
  
• Not reported to spread vegetatively
  
• Herbicides provide effective control
  
• Cultivation and mechanical methods may provide effective control