Yellow Alyssum is a member of the mustard family. An exotic imported from Europe, it threatens native grasses.
The plants grow from 4 to 8 inches in height and branch at the base. The leaves are narrow, strap-like, and covered with star-shaped hairs. In spring, yellow flowers are borne in racemes. Seeds are formed in silicles that are round, flattened and pointed at the top, much like a bellows. In summer, seeds drop out of the center of the pods, leaving a skeleton that resembles a pair of "spectacles."
Yellow alyssum has a taproot that can be easily hand-pulled from moist soil in the garden.
Post-emergent treatment with 2-4,D, or triclopyr is effective in controlling this weed in turfgrass. Yellow alyssum can be spot treated with glyphosate (Round-up, Kleen-up).
Photos: Judy Sedbrook
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010