alyssum, any species of the genus Alyssum of the family Cruciferae (mustard family), annual and perennial herbs native to the Mediterranean area. A few species, notably the perennial golden tuft (A. saxatile), are cultivated as rock-garden or border ornamentals for their masses of yellow or white flowers. The annual sweet alyssum (called A. maritima but separated by most botanists as Lobularia maritima) is a similar plant with fragrant white or lilac blossoms. The alyssums have been called madwort or heal-bite because of an old belief that they cured rabies. Alyssum is classified in the division Magnoliophyta, class Magnoliopsida, order Capparales, family Cruciferae.