Hoary alyssum is a tap-rooted perennial, biennial, or annual, that spreads through seeds. It produces small, white flower clusters that have four petals, which are deeply lobed. The plant has a rosette stage with leaves that get progressively bigger and have light colored mid ribs. The stems and leaves of hoary alyssum are very narrow and are covered with short, white hairs. The seeds are fairly large, oval-shaped, and laterally flattened. It is considered highly toxic to horses causing a number of different symptoms.
Hoary alyssum has been seen in Teton County aggressively moving along roadsides. Because it lacks foliage and is similar to other mustards in its early stages, this noxious weed can be very difficult to control.
For help managing infestations,
please call Teton County Weed & Pest District at 733-8419.