HOARY ALYSSUM (BERTEROA INCANA (L.) DC)
An erect, branched plant growing to 1.1m. A cluster of small white flowers forms at the top of slender stems from June to September. Flowers are 4-6mm long with deeply notched petals. Seed pods are 5-8mm long and covered in star-shaped hairs. The pods have chambers each containing 5-7 seeds. Plants are biennial (sometimes perennial), with a slender taproot.
Habitat and Ecology
Grows in disturbed habitats with coarse, dry soils, including roadsides, dry fields, hayfields, and pastures.
This plant is poisonous to horses, and can cause fever, limb edema and laminitis when eaten. Hoary alyssum usually increases in forage crops after a drought or winterkill event.
It is important to detect this plant early to prevent spread. Small populations can be killed through hand pulling or hoeing before the plants mature. Larger populations can be mowed to prevent seeding. A healthy forage stand will resist invasion by hoary alyssum. Herbicides can be applied in spring or autumn to the growing plants. Be sure to check with the BC Ministry of Agriculture, Food and Fisheries Crop Production Guides for herbicide recommendations.
Province of British Columbia. 2002. Guide to Weeds in British Columbia.
Photo reference: Catherine Herms, The Ohio State University, Bugwood.org