Elaeagnus is a genus of about 90 species of deciduous and evergreen shrubs and small trees in the family Elaeagnaceae (order Rosales). The genus was described by Carl Linnaeus in 1753 and is sometimes called the oleasters or silverberries. Most members are native to temperate and subtropical Asia, with a single species (E. commutata) native to North America, one (E. triflora) reaching northeastern Australia, and E. angustifolia possibly native to the easternmost fringes of Europe.
The most distinctive trait of the genus is the dense covering of tiny silvery to brownish peltate scales on the young shoots, leaf undersides, calyces, and developing fruits. This indumentum gives many species a frosted, metallic sheen that horticulturists prize. Leaves are alternate and simple, often leathery in evergreen species and softer in the deciduous ones. The flowers are small but typically strongly fragrant, with no true petals — a tubular, four-lobed calyx that is often cream, yellow, or white inside takes their place, and four stamens are inserted on the hypanthium.
After pollination the hypanthium thickens and becomes fleshy around the achene, producing what looks like a drupe with a single hard, bony seed. In many species this pseudodrupe is edible — red, pink, orange, or silvery and frequently scaly on the outside. The fruits of cultivated species such as E. umbellata, E. multiflora, and E. angustifolia are juicy, vitamin-rich, and contain lycopene and other carotenoids alongside flavonoids and essential fatty acids.
Ecologically, Elaeagnus is best known for its root symbiosis with nitrogen-fixing actinobacteria, which allows it to colonize poor, sandy, alkaline, and saline soils that would defeat most other woody plants. That same toughness — combined with tolerance of pruning, drought, salt spray, and shade — is what makes the genus so widely cultivated for hedging, screening, windbreaks, and ornamental foliage, and what makes a handful of species (notably E. angustifolia, E. umbellata, and E. pungens) aggressive invaders outside their native range.
Etymology
The genus name Elaeagnus was coined by Carl Linnaeus when he published Species Plantarum in 1753, but the word itself is much older. It is a Latinisation of a Greek plant name used by Theophrastus, built from ἐλαία (elaía, "olive") plus a second element whose origin is debated — it may echo Vitex agnus-castus (the chaste tree) or refer to a kind of willow. The compound essentially means something like "olive-willow" or "olive-like," and it captures the silvery, narrow-leaved appearance that some species, especially the Russian olive (E. angustifolia), share with the true olive.
Distribution
The genus has its centre of diversity in temperate and subtropical Asia, where the great majority of its species occur — China alone hosts dozens of endemics. From that core the range extends west to the eastern Mediterranean, with E. angustifolia possibly indigenous to southeasternmost Europe, and east into Japan, the Philippines, and Indonesia. A single outlier, E. triflora, reaches northeastern Australia, and one species, E. commutata (the American silverberry), is genuinely native to North America. Several Asian species — most notably E. angustifolia, E. umbellata, and E. pungens — have been introduced widely as ornamentals and shelterbelt plants and are now naturalised across much of North America, Europe (including Switzerland, where the genus is entirely non-native), and other temperate regions.
Ecology
The defining ecological trait of Elaeagnus is its root symbiosis with actinobacteria of the genus Frankia, which fix atmospheric nitrogen inside small root nodules. This frees the genus from the nitrogen limitations that constrain most woody plants and explains how species can thrive on disturbed, sandy, salt-laden, alkaline, or otherwise impoverished soils. Interplanting Elaeagnus among fruit trees has been reported to raise yields by roughly ten percent in plum and nut orchards through this nitrogen contribution. The fleshy, lipid-rich fruits are eaten by many bird species, which disperse the seeds efficiently — a major reason the introduced Asian species spread so quickly outside cultivation. Thorny taxa also provide dense nesting and roosting cover for birds, and the foliage supports the larvae of a number of Lepidoptera.
Cultivation
Elaeagnus is one of the most forgiving woody genera in cultivation. Species span an enormous hardiness range (USDA zones 0–11) and tolerate sand, loam, or clay; full sun to part shade; drought and waterlogging; and alkaline or saline conditions that few other shrubs accept. They take hard pruning well, which makes them favourites for clipped or informal hedges, windbreaks, coastal shelter plantings, and large evergreen screens. The silvery undersides of the leaves are an ornamental feature in their own right, and variegated cultivars of E. pungens and the hybrid E. × submacrophylla (which holds the RHS Award of Garden Merit) are widely grown for foliage colour. The genus is also planted in agroforestry systems to enrich soil nitrogen and for its edible, vitamin-rich fruit — E. angustifolia, E. multiflora, and E. umbellata are the species most often grown for that purpose, with named selections including thornless forms.
Propagation
Most Elaeagnus species can be raised from seed, but germination is slow: fresh seed is preferred, and stored seed typically needs a warm period of about four weeks followed by twelve weeks of cold stratification, after which it may still take up to eighteen months to emerge. Vegetative methods are widely used. Half-ripe cuttings taken in July or August and mature-wood cuttings taken in October or November will root, though success is often low and slow. Layering is reliable but typically takes about a year to produce a self-supporting plant, and root cuttings can be taken during winter dormancy.
Conservation
The conservation story for Elaeagnus is dominated by invasiveness rather than threat. Several Asian species — particularly E. angustifolia (Russian olive), E. umbellata (autumn olive), and E. pungens (thorny olive) — were planted heavily through the twentieth century for wildlife habitat, erosion control, and ornament, and have since escaped into wild systems across North America and parts of Europe. They are classified as category II noxious, invasive species in parts of the United States, and InfoFlora tracks them on Switzerland's invasive neophyte monitoring lists. Their nitrogen-fixing ability is itself part of the problem: it alters soil chemistry and gives invading stands a competitive edge over native vegetation adapted to lower-nutrient sites.
Cultural uses
Several Elaeagnus species are food plants. The fruits of E. umbellata, E. multiflora, and E. angustifolia are eaten fresh, dried, or made into jams and beverages; E. umbellata fruit is notably high in lycopene and other carotenoids in addition to the vitamins A, C, and E, flavonoids, and essential fatty acids common across the genus. Seeds and flowers have a history of use in traditional medicine, and modern phytochemistry has investigated extracts for potential anticancer activity. The plants themselves are widely used in shelterbelt and reclamation plantings on degraded land, exploiting the same nitrogen-fixing biology that powers their fruit production.
Taxonomy notes
Elaeagnus L. is the type genus of the small family Elaeagnaceae (order Rosales), alongside Hippophae and Shepherdia. GBIF lists 156 descendant taxa under the genus key 3039266; recent estimates of accepted species cluster around 90 (Wikipedia notes 93 accepted as of late 2025), although older treatments such as the SEINet description recognise only about 45 species — a reminder that species delimitation in this taxonomically difficult, largely Asian genus is still unsettled. A doubtful later homonym "Elaeagnus Hill" is recorded in the GBIF backbone but is not accepted.
