Photo Credit: Nicole Kimmel, Alberta Agriculture & Forestry
Common Name: Hoary Alyssum
Scientific Name: Berteroa incana
Habitat: roadsides, disturbed areas, grassland, dry grassland
Provincial Designation: Prohibited Noxious
Prohibited Noxious weeds are plant species designated in the Alberta Weed Control Act. Prohibited noxious weeds must be destroyed when found, meaning all growing parts need to be killed or the plant's reproductive mechanisms need to be rendered non-viable.
Hoary Alyssum is native to Eurasia and was most likely introduced to North America in the late 1800s as a seed contaminant.
It is invasive in open grassland and can become a problem in rangelands. It is toxic to horses. It is a weed of alfalfa and clover forages, reducing their quality with its nutrient-poor herbage. It competes with native flora and reproduces continuously. It may reduce pollinators.
Hoary Alyssum's flowers are arranged in round clusters, are small, white, and have four deeply notched petals.
The leaves are grey-green in colour, covered with star-shaped hairs, and are alternately arranged along the stem. They clasp the stalk without any stem.
The fruits are flat, elliptical and covered in hairs.
The stem can reach 30-90 cm tall and is also covered with star-shaped hairs.
Can Be Confused With
- Sweet Alyssum - Lobularia maritima - which is an ornamental garden plant and fine for you to grow! Hoary Alyssum has two lobes on each petal and does not have a noticeable smell.