Hoary alyssum, a member of the mustard family, 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 toxic to horses causing a number of different symptoms. Please contact SCWP to learn how to help manage this invasive weed, what works best in your area and how to use it safely.