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Hoary Alyssum

Hoary Alyssum

Hoary Alyssum

(Berteroa incana)

Priority: -  Contain

Tags: Terrestrial | Toxic

Identification and Reproduction


  • Annual to short-lived perennial, up to 80 cm tall. 
  • Grows from a taproot
  • Stems are covered in hairs and branch from the base. 
  • Leaves are greenish-grey, slender with round tips and arranged alternately. Leaves will decrease in size moving closer to the stem tip. 
  • Can over-winter as a rosette, then emerge again in spring
  • Flowers are found in small white clusters near the stem tips. They are composed of 4 small white petals that are each notched. 
  • Seedpods are oval-shaped, have 5-7 black seeds 


Seeds spread by people, equipment, and wildlife.

Habitat & Ecology

  • Establishes in sandy, gravelly soils, and pastures. 
  • Long seed production season.


  • Invades forage and rangeland.
  • Toxic, harmful to horses, which can be very problematic.


Mechanical/Manual Control:

  • When infestations are small hand pulling is effective. Note that entire root crown must be removed. 
  • Burning of mature plants has proven to destroy seeds. 
  • Avoiding mowing mature plants as roots will persist and regrow. 


Download A Guide to Weeds in British Columbia for Hoary Alyssum here.

Download the Equine Program Newsletter from the Michigan State University on Toxicity, Identification and Control of Hoary Alysumm in Forages here.

Header photo (Molekuel). 

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