Elaeagnus is a genus of about 50–70 species of flowering plants in the family Elaeagnaceae. Species of the genus are commonly known as silverberry or oleaster,

Description

Elaeagnus plants are deciduous or evergreen shrubs or small trees. The alternate leaves and the shoots are usually covered with tiny silvery to brownish scales, giving the plants a whitish to grey-brown colour from a distance. The flowers are small, with a four-lobed calyx and no petals; they are often fragrant. The fruit is a fleshy drupe containing a single seed; it is edible in many species. Several species are cultivated for their fruit, including E. angustifolia, E. umbellata, and E. multiflora (gumi). E. umbellata contains the carotenoid lycopene.

Taxonomy

The genus Elaeagnus was erected in 1754 by Carl Linnaeus, who attributed the name to Joseph Pitton de Tournefort. There is agreement that the name is based on Theophrastus's use of the Ancient Greek ἐλαίαγνος (, latinized to ) as the name of a shrub. The first part of the name, elae-, is from ἐλαία, 'olive'. Sources differ on the origin of the second part: it may be from ἄγνος, Vitex agnus-castus, the chaste tree, or from the Greek name for a kind of willow. In either case, the second part is derived from ἁγνός, meaning 'pure', 'chaste'.

Species

Elaeagnus comprises the following species:

Species names with uncertain taxonomic status

The status of the following species is unresolved:

Hybrids

The following hybrids have been described:

Habitat

The vast majority of the species are native to temperate and subtropical regions of Asia. Elaeagnus triflora extends from Asia south into northeastern Australia, while E. commutata is native to North America, and Elaeagnus philippinensis is native to the Philippines. One of the Asian species, E. angustifolia, may also be native in southeasternmost Europe, though it may instead be an early human introduction there. Also, several Asiatic species of Elaeagnus have become established as introduced species in North America, with some of these species being considered invasive, or even designated as noxious, in portions of the United States.

Ecology

Elaeagnus species are used as food plants by the larvae of some Lepidoptera species including Coleophora elaeagnisella and the Gothic moths. The thorny shrubs can also provide good nesting sites for birds.

Nitrogen fixation

Many Elaeagnus species harbor nitrogen-fixing organisms in their roots, so are able to grow well in low-nitrogen soils. This ability results in multiple ecological consequences where these Elaeagnus species are present. They can become invasive in many locations where they are established as exotic species. Two species (E. pungens and E. umbellata) are currently rated as category II noxious, invasive species in many world regions and by the Florida Exotic Pest Plant Council.

Cultivation

Elaeagnus species are widely cultivated for their showy, often variegated, foliage, and numerous cultivars and hybrids have been developed. The fruit is acidic and somewhat astringent. It makes good tarts. Notable species and hybrids in cultivation include:- The hybrid Elaeagnus × submacrophylla and the cultivar 'Gilt Edge' have gained the Royal Horticultural Society's Award of Garden Merit.