What is "sweet alyssum"

Alyssum \A*lys"sum\ ([.a]*l[i^]s"s[u^]m), n. [NL., fr. Gr. 'a`lysson, name of a plant, perh. fr. 'a priv. + ly`ssa raging madness.] (Bot.) A genus of cruciferous plants; madwort. The sweet alyssum ( Alyssum maritimum), cultivated for bouquets, bears small, white, sweet-scented flowers.

n. perennial European plant having clusters of small fragrant usually white flowers; widely grown in gardens [syn: sweet alison, Lobularia maritima]