noun. Any of various chiefly Mediterranean weeds or ornamentals of the genus Alyssum in the mustard family, having racemes of white or yellow flowers.

noun. Any of various similar plants in the mustard family, especially sweet alyssum.

noun. Any of several plants, of the genus Alyssum, that have racemes of white or yellow flowers.

"Provide a mixture of nectar and seed rich flowering plants such as alyssum, sunflower and knapweed, which will attract insects and also provide seed for birds to feed on."

madwort  

hoary alyssum  sweet alyssum