Lobularia is a plant genus that is part of the Brassicaceae family. It contains about four species of annual and perennial flowering plants that are native to the Mediterranean region and Macaronesia. The plants in this genus have a compact, mat-forming structure that consists of aromatic flowers and gray-green leaves. Landscapers utilize these plants in flower beds, borders, and rock gardens. This genus is susceptible to pest infestation and fungal disease.
The genus name is a Latin word that means "a small pod," which refers to the seedpod produced by these plants. Commonly, the plants in the Lobularia genus are known as sweet alyssum. Varieties of Lobularia maritima have slight variations on the name. The variety of Lobularia maritima that produces white flowers is known as "sweet white," and the pinkish colored variety is called "Rosie O'Day."
Most of the species are native to the islands in the north Atlantic Ocean, off the coast of northwestern Africa. Lobularia canariensis populates most of the Canary Islands and Cape Verde. Lobularia maritima grows on the island of Malta and Gozo in the Mediterranean Sea.
Generally, the plants in this genus grow about 4 inches (10 cm) in height and spread about 6 inches (15 cm). They grow low to the ground. The leaves are small and arranged in an alternating fashion on the lower part of the stem. The stems are rigid and branched at multiple points, with flowers sitting at the tips.
The flowers are comprised of four petals that are circular in shape. They grow in clusters and are honey-scented. Hoverflies are attracted to the aromatic flowers.
L. maritima is a commonly cultivated species in the Lobularia genus. It requires well-draining soil that is moderately fertile. Usually, loamy or sandy soil that is acidic or alkaline provides sufficient support for this plant. It does best in an area that is sheltered from the wind and exposed to direct sunlight.
A common problem with growing sweet alyssum is protecting it from aphids, which are small, round insects that feed on the leaves of the plant. They usually leave a sticky residue on the leaves and branches that attracts fungal spores. Spraying an insecticidal soap on the foliage usually prevents the infestation from spreading.
Another problem with this species is the risk of contracting downy mildew, a fungal infection. It is a white mold that develops on the leaves of the plant. Beneath the mold, the leaf will appear yellow.