Elaeagnus × ebbingei (E. × submacrophylla) 'LEMON ICE' evergreen silverthorn
Symbivit Tric (arbuscular)
Symbivit (arbuscular)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.
If you are fond of variegated cultivars of evergreen silverthorns, e.g., Limelight, there is an improved version of it called Lemon Ice. It has slightly broader leaves and a more upright growth and bushier, more compact habit. The leaves have dark green margins and a light to medium deep yellow interior that can take up to 80% of the leaf surface. They are evergreen, leathery, glossy, and rather flat (not undulate). Young leaves emerge pale beige and exhibit tiny dots as if sprinkled with stardust. They are fully coloured withing approximately 4-6 weeks. Like most variegated plants, Lemon Ice silverthorn, too, occasionally produces reversed branches with green leaves. Those are more vigorous and need to be removed as soon as spotted as they might suffocate and overgrow the coloured part of the plant. The orange-brown color of the twigs is more pronounced with the arrival of cool autumn weather.
Silverthorns are valued not only for their colourful leaves and fast growth, but they also offer flowering in autumn. The flowers are small and inconspicuous, but their fragrance is from heaven. On warm and sunny autumn days, it releases a very pleasant and sweet scent, something between carnation, lilac and jasmine, in the area of a few meters around it. If the winter is mild, small, edible fruits ripen during May. They are deep red, approx. 1.5 cm long ovals with a stone. The taste is reminiscent of sour cherries but sweeter, and they are best when they start to fall off shrub – then they are fully mature.
Silverthorns are nice specimen shrubs as well as great hedging plants. Suitably combined with other shrubs with contrasting foliage colour they do a great job. Mix them together with photinias, laurels, large- and small-leaved hollies, or hardy eucalyptus. Together, they will create a unique, evergreen, and attractive hedge that will look great throughout the year.
Evergreen silverthorn is one of the toughest evergreen shrubs and thrives in almost any well‑drained soil – from sandy to loamy to stony, ideally with neutral to slightly alkaline pH. It grows best in full sun but also tolerates partial shade very well and will grow even in deeper shade, only becoming slightly looser. After planting it needs regular watering only for a few months to establish, and afterwards watering should be avoided completely – it is highly tolerant of drought and wind. It dislikes heavy, airless and permanently wet soil, where it becomes prone to problems and grows poorly. It tolerates pruning extremely well, with the best time being early spring before growth starts, and throughout the season you can shorten over‑long shoots without concern. Mulching with a 5–7 cm layer helps retain moisture, improves soil structure, supports density and protects against rapid winter temperature fluctuations. It is hardy to about –24 °C (USDA zone 6) and can withstand even a few degrees lower for short periods, with the risk of shoot tips freezing, but it regenerates very well in spring.
Last update 09-09-2022
