Botany and names
Lobularia maritima is a species of low-growing flowering plant in the family Brassicaceae. Its common name is sweet alyssum or sweet Alison. It is also commonly called just alyssum, from the genus Alyssum in which it was formerly classified. The genus name Lobularia comes from a Greek word meaning 'small pod', referring to the shape of the fruits. The name of the species, maritima, refers to its preferred coastal habitat. It belongs to the order Brassicales. The genera Lobularia, Aurinia and Odontarrhena are closely related to Alyssum and were formerly included in it. The common rockery plant known as Alyssum saxatile is Aurinia saxatilis.
Lobularia maritima is an annual plant, rarely a short-lived perennial, growing to 5-30 cm tall by 20-30 cm broad. The stem is very branched, with dense clusters of small flowers. The flowers are produced throughout the growing season, or year-round in areas free of frost. They are pollinated by insects, as their honey-like fragrance is attractive to bees, flower flies, stingless wasps and butterflies. The fruits are numerous elongated seedpods rather hairy, oval to rounded, each containing two seeds. The leaves are 1-4 cm long and 3-5 mm broad, alternate, sessile, quite hairy and oval to lanceolate, with an entire margin. Each flower has four sepals and six stamens with yellow anthers. The seeds are dispersed by the wind.
The family and the genus Alyssum
Brassicaceae is a medium-sized family of flowering plants commonly known as the mustards, the crucifers or the cabbage family. Its flowers have four free sepals and four free alternating petals. The family also includes ornamentals, among them Alyssum and Lobularia.
The genus Alyssum itself holds over a hundred species, native to temperate Europe, Asia and northern Africa, with the highest diversity in the Mediterranean region. They are annual and perennial herbaceous plants or, rarely, small shrubs, 10-100 cm tall, with oblong-oval leaves. Their small flowers are grouped in terminal clusters and are often yellow or white, but can be pink or purple.
Distribution, habitat and cultivation
Lobularia maritima is widely naturalized elsewhere in the temperate world, including the United States. An endemic subspecies grows in the local flora of the Columbretes Islands of the western Mediterranean. It is common on sandy beaches and dunes, but can also grow on cultivated fields, walls, slopes and waste ground. It grows preferably on calcareous soil, at an altitude of 0-300 metres above sea level. The plant is a halophyte: it tolerates high concentrations of salt, up to 400 mM, and is common on the Tunisian coast.
It is cultivated in gardens, with many horticultural varieties with purple or pink flowers. When grown in gardens, it is typically used as groundcover, as it rarely grows higher than 20 cm. It is best planted in early spring and requires little maintenance. Although an annual, it may reseed in temperate climates, and it flowers more profusely if spent blooms are trimmed. It is also grown in cracks in paving and walls, and is highly resistant to heat and drought. Clusters of tiny white, pink or purple flowers bloom continuously from winter through spring. Plants do best in well-drained soil and flower most when watered regularly and fertilized. Sweet alyssum is generally pest free and reportedly deer resistant. The old seed-grown types perform poorly compared with newer types that are propagated from cuttings. Named cultivars include 'Snow Crystals', 'Snowdrift', 'Royal Carpet' (purple), 'Snow Cloth' (white) and 'Violet Queen'. The petals, leaves, and tender stems of the plant can be eaten raw or cooked.
Essential oil
Linalool is the major component of the essential oil of the aerial parts, accounting for 22.43% of the whole oil. The oil also holds benzyl alcohol (8.65%), 1-phenyl butanone (7.33%) and γ-terpinene (6.15%). The major components also include α-cadinol (4.91%), globulol (4.32%) and terpinen-4-ol (4.31%). Further components include α-terpineol (3.9%), ledol (3.59%), α-pinene (3.51%), pulegone (3.33%) and epi-α-cadinol (3.05%).
In the β-carotene bleaching test, the oil's antioxidant activity was dose dependent. In rats given carbon tetrachloride, a dose of 250 mg per kg body weight reduced the toxic effects and the oxidative stress on the liver. The oil showed no signs of toxicity in acute tests up to a dose of 2000 mg per kg. In macrophages stimulated with lipopolysaccharide, which raised the levels of the proteins COX-2 and iNOS, treatment with the oil lowered the expression of these proteins.
Tested against food-borne bacteria, the oil showed strong antimicrobial activity against eight pathogenic strains. This activity was attributed mostly to benzyl alcohol, linalool, terpinen-4-ol and globulol, together with the combined effect of its major and minor constituents. Added to ground beef at 0.076%, the oil extended the shelf life of the meat stored at 4 °C.
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