Hoary Alyssum (Berteroa incana)

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Toxic to Horses

Hoary alyssum grows to 0.7 m and has white flowers carried on long slender stalks. Oval seedpods are flattened and held close to the stem. Leaves are grey-green in color. The entire plant is covered in star-shaped hairs.

Most common on sandy or gravelly soils, hoary alyssum establishes in dry, disturbed habitats, such as roadsides and railway embankments. It is also found on meadows, pastures, and hayfields.
Key Identifiers
  • White petals are deeply notched at apex
  • Hoary appearance of stem, leaves and pods from gray, star shaped pubescence
  • Stalk-less, non-clasping leaves with entire margins
  • Membranous partition in seed pods, obvious after seed has fallen.
  • 4-12 seeds in seed pods
Location in Canada
In Canada, hoary alyssum has been reported in all provinces except Nfld and PEI. Alberta had old reports of locations in and around Drumheller. In 2011, there have been several reports of Hoary alyssum in the M.D. of Wainwright.


Nicole Kimmel, ARD

Nicole Kimmel, ARD

Nicole Kimmel, ARD
Similar species
Alyssum sp. Pale alyssum (Alyssum alyssoides), desert alyssum (Alyssum desertorum), and wall alyssum (Alyssum murale) resemble hoary alyssum, but they are smaller plants with much smaller seed pods (at most 4 mm long) that carry only 1–2 seeds/chamber. Wall and desert alyssum have yellow flowers. efloras.org - Alyssum
False flaxes (Camelina sp.) differs by having seed pods 90° to stem, yellow flowers and clasping leaves. Canada grows camelina for biodiesel production.wikipedia.org - Camelina sativa
Stinkweed (Thlaspi arvense) leaf margins are toothed and seedpod is winged. Alberta grows stinkweed/pennycress for biodiesel production. anpc.ab.ca/wiki - Stink Weed

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For more information about the content of this document, contact Chris Neeser.
This document is maintained by Shelley Barkley.
This information published to the web on April 10, 2012.
Last Reviewed/Revised on August 21, 2018.