Hoary Alyssum

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.

Origin

Hoary Alyssum is native to Eurasia and was most likely introduced to North America as a seed contaminant.

Legislated Because

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.

Description

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. 

Learn more about this species:

See Fact Sheet - Alberta Invasive Species Council