Elaeagnus × ebbingei (E. × submacrophylla) 'COASTAL GOLD' evergreen silverthorn

Elaeagnus

The genus Elaeagnus, oleaster, belongs to the oleaster family and includes roughly ninety species distributed from south‑eastern Europe to Japan. It is an ancient group of woody plants, as shown by Tertiary fossils indicating that oleasters were once common even in regions where they no longer grow today. The whole genus is characterised by tiny scales on the leaves and young shoots, giving the plants a silvery or rusty sheen while protecting them from sun and drought. Oleasters also belong among the woody plants capable of supplying part of their own nitrogen: their roots host symbiotic bacteria of the genus Frankia, which can convert atmospheric nitrogen into a usable form. Thanks to this, oleasters thrive even in poor, sandy or windy soils where many other shrubs would struggle. The genus was first defined in 1700 by Joseph Pitton de Tournefort (1656–1708), one of the most important pre‑Linnaean systematists, professor of botany at the Jardin du Roi in Paris and author of the first truly functional plant classification system based on clearly defined genera. In his major work Éléments de botanique he separated oleasters from related genera and gave them the name Elaeagnus, later adopted and formally established by Carl Linnaeus.

Within the genus, some species can hybridise, and the most vigorous combination proved to be E. macrophylla crossed with E. pungens. From the first parent the hybrid inherited large, leathery, evergreen leaves, and from the second its notable toughness, resilience and ability to regenerate quickly after pruning. Botanically it is a stable, repeatedly occurring hybrid that appears naturally wherever the ranges of the two parent species overlap, and in cultivation it has become one of the most widely grown evergreen shrubs of the temperate zone.

The history of this hybrid, commonly called evergreen silverthorn, is intriguingly tangled and shows how differently botanical and horticultural naming can develop. The Swiss botanist Camille Servettaz (1870–1947) described in 1909 a plant with strikingly large leaves under the name Elaeagnus × submacrophylla, without realising at the time that it was a hybrid. She treated it as an unexplored taxon because it matched neither E. macrophylla nor E. pungens, yet clearly bore traits of both. Only later revisions revealed that her description precisely matched what we now recognise as the hybrid of these two species. Meanwhile, the horticultural world took a different path. The prominent Dutch botanist and breeder Simon Doorenbos (1891–1980) sowed in 1929 seeds of oleasters growing together in The Hague municipal nursery and among the seedlings found a plant that differed markedly from the rest. Realising its hybrid origin, he named it Elaeagnus × ebbingei in honour of his colleague J. W. E. Ebbinge. The name quickly caught on because Doorenbos’s plants spread through European nurseries and became the backbone of modern hedges in coastal and urban areas. Only modern studies showed that Doorenbos’s name does not have botanical priority, as Elaeagnus × submacrophylla had been published earlier and is therefore considered correct. Although botanical databases and gardens now use Servettaz’s name, the powerful horticultural trade continues to work with the traditional name E. x ebbingei, and it remains uncertain if or when it will shift to E. × submacrophylla.