Elaeagnus pungens
(thorny olive)

Pictures

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Identity

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Preferred Scientific Name

• Elaeagnus pungens Thunb., 1784

Preferred Common Name

• thorny olive

Other Scientific Names

• Elaeagnus pungens var. simonii (Carrière) Rehder
• Elaeagnus simonii Carrière

International Common Names

• English: leathery silver-bush; pungent elaeagnus; silverberry; silverthorn; spotted elaeagnus; thorny elaeagnus
• Chinese: hu tui zi

Local Common Names

• Germany: Ölweide, Dornige
• Japan: nawashiro-gumi

EPPO code

• ELGPU (Elaeagnus pungens)

Summary of Invasiveness

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E. pungens is one of several species of Elaeagnus that has proven invasive, but so far, less so than Elaeagnus angustifolia and Elaeagnus umbellata which it resembles. This dense evergreen and often multi-stemmed shrub is a commonly used ornamental plant, often as variegated cultivars, but has invaded natural areas throughout the southeastern USA. It is very tolerant of wind, salt and shade, but will invade both in open areas and in forests. The fruit is widely consumed by animals and can spread rapidly.

Taxonomic Tree

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• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Elaeagnales
•                         Family: Elaeagnaceae
•                             Genus: Elaeagnus
•                                 Species: Elaeagnus pungens

Notes on Taxonomy and Nomenclature

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Elaeagnus is placed in its own family, the Elaeagnaceae, also containing the genera Hippophae and Shepherdia. There are about 80 species within the genus with a wide distribution in eastern Asia (Zheng et al., 2006). Elaeagnus pungens is placed in section Sempervirentes (Tzvelev, 2002). Being a respected ornamental species, there are a number of cultivars including probably the most widespread, cv. Maculata, but also Aurea, Dicksonii, Frederici, Fruitlandii, Gold Rim and Variegata amongst others. These are sometimes given higher ranks such as form or variety, and subspecies have also been proposed. For the purposes of this datasheet, a single undivided species is accepted with numerous cultivars. It is most commonly known as the thorny olive or silverberry.

Description

Top of page E. pungens is an evergreen densely branched shrub commonly 3-4 m, but it can be as small as 1 m, and occasionally up to 8 m tall. Spines are frequent on the stems. Young branches densely brown scaly, pubescent when young. Leaves thick and leathery, silver-brown, alternate, oval, elliptical or oblong, 5-10 cm long and 1.8-3.5 (-5) cm wide, with dense whitish scales also often brown, glabrous and glossy above, scaly underneath, lateral veins 7-9 each side of midrib, base rounded, irregular undulate margins, apex obtuse to bluntly acute. Petioles robust, 4-5 (-15) mm long. Flowers fragrant, silvery-white to brown, tubular and 1 cm long, few (1-3), in axillary clusters, pedicel 5-8 mm and scaly brown, calyx tube 6-7 mm long and abruptly narrowed at base, lobes ovate, apex rounded. Fruit oblong, 1.0-1.5 cm, brown scaly containing one nut, white changing to red with spotted brown scales when ripe (adapted from Miller, 2003; Flora of China Editorial Committee, 2008).

Plant Type

Top of page Broadleaved
Perennial
Seed propagated
Shrub
Tree
Woody

Distribution

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E. pungens is native to China and Japan. It has been introduced to the eastern and southeastern USA were it is widely reported, is noted in New Zealand, and also in some European countries with unconfirmed reports from others. Noting its ornamental value and tolerance to drought and saline conditions, it is likely to be present in many more countries than is indicated, especially in northern Europe, but also around the Mediterranean, western USA, Canada, and elsewhere.

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

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E. pungenswas first introduced into the USA in 1830 as an ornamental, and it was thought to have been introduced into Europe between 1829 and 1866, first to the Netherlands, by the Bavarian physician Philipp von Siebold who introduced numerous garden plants from Japan into Europe (Christenhusz and Uffelen, 2001). It was also introduced to New Zealand, and to Israel (Hagiladi et al., 1989), though exact dates are not known.

Risk of Introduction

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E. pungens is on the Florida and South-East Exotic Plant Pest Council list of invasive plants (USDA-NRCS, 2008), and is also on exotic pest lists for several other states including Alabama, Georgia, South Carolina, Tennessee and Virginia. As a highly valued ornamental it is highly likely to continue to be introduced as any number of the existing or future selected cultivars.

Habitat

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In its native range, E. pungens is often found on open slopes, roadsides or thickets, often near the sea and generally below 1000 m (Flora of China Editorial Committee, 2008). Where introduced and invasive it is also found in scrub and shrublands, and natural forests.

Habitat List

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Category	Sub-Category	Habitat	Presence	Status
Terrestrial
	Terrestrial – Managed	Rail / roadsides	Present, no further details	Harmful (pest or invasive)
	Terrestrial ‑ Natural / Semi-natural	Natural forests	Present, no further details	Harmful (pest or invasive)
		Natural grasslands	Present, no further details	Natural
		Scrub / shrublands	Present, no further details	Harmful (pest or invasive)
		Scrub / shrublands	Present, no further details	Natural
Littoral
		Coastal areas	Present, no further details	Harmful (pest or invasive)
		Coastal areas	Present, no further details	Natural
		Coastal dunes	Present, no further details	Harmful (pest or invasive)
		Coastal dunes	Present, no further details	Natural

Biology and Ecology

Top of page Genetics

A number of cultivars have been selected and propagated, mostly for variegated foliage. Of these, cv. Maculata and cv. Dicksonii are slower growing variegated forms that also produce good fruit crops, cv. Frederici has especially large fruit 25 mm long, and there are other cultivars including Aurea, Clemson Variegated, Fruitlandii, Gold Rim, Hoksuba Fukurin, Tricolor and Variegata. Frederici is an old cultivar and may have been the original sent to the Netherlands by von Siebold in the mid 1800s (Houtman, 2004). The cultivated hybrid Elaeagnus x ebbingei arose from a cross between E. macrophylla, and pollen from E. pungens and was distributed in 1938 through M Koster and Sons of Boskoop, the Netherlands (Houtman, 2004). Chromosome numbers are not reported.

Reproductive Biology

The scented flowers are hermaphrodite and are pollinated by bees.

Physiology and Phenology

Although commonly described as an evergreen, it may be deciduous in some circumstances. In its native range in China it flowers in September-December and fruits in April-June (Flora of China Editorial Committee, 2008). Where invasive in the USA it flowers in November-February and fruits in April-May. It is a nitrogen-fixing species, via an association with actinomycete fungi. After germination it produces dense multiple stems, with short shoots and small leaves that become branched or unbranched thorns 1-4 cm long. In the second year, lateral branches are produced that are followed by flowers in the autumn (Miller, 2003). It is extremely wind resistant and salt resistant (Houtman, 2004).

Associations

It is a nitrogen-fixing species, in association with actinomycete fungi, Frankia spp. (Dommergues et al., 1999), that also nodulate Hippophae and Shepherdia, but not by strains that colonize other actinorhizal plants such as Casuarina and Alnus. Inocula is available for Elaeagnus species, although inoculation may not be necessary since most plants spontaneously nodulate in the nursery or upon planting in the field, and unlike Rhizobium, Frankia survive in the soil for long periods without the presence of host plants. Specific E. pungens strains were identified by Fukumoto et al. (1995).

Environmental Requirements

E. pungensis a species of warm temperate climates, and drought tolerant but can grow in most soils. It prefers a variety of soil types but prefers well-drained soils, and can tolerate infertile and very heavy soils, acid and alkaline conditions, and exposure to salt winds.

Climate

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Air Temperature

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Rainfall

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Rainfall Regime

Top of page Bimodal
Summer
Uniform
Winter

Soil Tolerances

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Soil drainage

• free
• impeded

Soil reaction

• acid
• alkaline
• neutral

Soil texture

• heavy
• light
• medium

Special soil tolerances

• infertile
• saline
• shallow
• sodic

Natural enemies

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Notes on Natural Enemies

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There are few records of pests and diseases specifically attacking E. pungens, though further investigation into horticultural diseases affecting ornamental plants would yield additional results. Colletotrichum gloeosporioides [Glomerella cingulata] was first identified as the causal agent of anthracnose in Argentina by Carmona and Wright (1999), and E. pungens was first identified as a new host record for Fusarium solani by Miller (1997).

Means of Movement and Dispersal

Top of page Vector Transmission (Biotic)

E. pungensseeds are dispersed by animals (Miller, 2003).

Intentional Introduction

It was introduced intentionally as an ornamental species around the world.

Pathway Causes

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Impact Summary

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Economic Impact

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As a valued and widely commercialised ornamental species, it has a clear positive economic impact as a traded product in the horticultural industry, though no data is available. However, native alternatives are available in all countries where it is introduced and currently sold.

Environmental Impact

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E. pungens invades natural environments and suppresses native vegetation. There are also unconfirmed reports of it being able to develop a climbing habit, and that it can climb to the tops of trees in northern Italy.

Threatened Species

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Social Impact

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The only social impacts are positive, from the aesthetic value as an ornamental species, and especially in coastal gardens in northern Europe where few other variegated plants can tolerate the harsh conditions.

Risk and Impact Factors

Top of page Invasiveness

• Proved invasive outside its native range
• Highly adaptable to different environments
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Highly mobile locally
• Fast growing
• Has high reproductive potential
• Has propagules that can remain viable for more than one year
• Has high genetic variability

Impact outcomes

• Damaged ecosystem services
• Ecosystem change/ habitat alteration
• Modification of fire regime
• Modification of nutrient regime
• Modification of successional patterns
• Monoculture formation
• Reduced native biodiversity
• Threat to/ loss of native species
• Transportation disruption

Impact mechanisms

• Competition - monopolizing resources
• Competition - shading
• Rapid growth

Likelihood of entry/control

• Highly likely to be transported internationally deliberately
• Difficult/costly to control

Uses

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E. pungens is mainly used for ornamental purposes, and is still a valued ornamental plant in the south-eastern USA from Maryland to Florida, where it is often used in parking lots and in highway medians. In northern Europe, its extreme wind resistant and salt resistant makes it one of the most preferred plants for coastal areas, especially the variegated cultivars (Houtman, 2004).

Uses List

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Environmental

• Amenity
• Ornamental
• Wildlife habitat

Human food and beverage

• Fruits

Ornamental

• Propagation material

Similarities to Other Species/Conditions

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E. pungens closely resembles the two other commonly introduced Elaeagnus spp., E. angustifolia and E. umbellata but the latter are generally deciduous and have thin, non-leathery leaves.

Prevention and Control

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Control

There are few reports of specific control methods for E. pungens, however, it could be assumed that cultural, mechanical and chemical treatments effective on the related E. angustifolia and E. umbellata would also be useful on E. pungens, especially those for E. umbellata as it occupies more similar climates and habitats. Control will need monitoring and repeated treatments to achieve success, and because seeds can be dispersed long distances by animals, it should also be eradicated in surrounding areas. Control can likely be achieved through eradication of individuals by hand pulling or spot applications of herbicide.

Cultural control

Hand-pulling of smaller plants would be effective, but as plants will resprout, mechanical or physical means that do not remove the roots are unlikely to be effective. Fire may also be appropriate (Munger, 2003).

Biological control

Zheng et al. (2006) have identified a range of natural enemies of E. pungens from its native range in China, some of which may prove effective as biological control agents.

Chemical control

Several herbicides have been used alone or in combination to provide effective control of E. umbellata and which may also prove effective on E. pungens (see Sather and Eckardt, 2001; Munger, 2003). Dicamba, glyphosate or 2,4-D (but not metsulfuron methyl) have been used as effective foliar-applied herbicides especially on shorter plants. On larger plants, glyphosate, triclopyr and/or 2,4-D are used effectively on regrowth; also basal-bark applications of triclopyr. In an invaded tree plantation in Illinois, USA, triclopyr reduced E. umbellata from 12.5 to 3.9 stems/m², but it is recommended that intensive control efforts focusing on relatively small areas in large well-established populations are only moderately effective and control efforts must be repeated every 5 years to achieve eradication (Edgin and Ebinger, 2001).

References

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Carmona MA, Wright ER, 1999. Occurrence of anthracnose on eleagnus under water deficit in Argentina. (Ocurrencia de la antracnosis del eleagno en condiciones de stress hídrico en Argentina.) Fitopatologia Brasileira, 24(4):574.

Christenhusz MJM, Uffelen GAvan, 2001. Naturalized Japanese plants in the Netherlands, introduced by Von Siebold. Gorteria, 27(5):97-108.

Clawson ML, Benson DR, Resch SC, Stephens DW, Silvester WB, 1997. Typical Frankia infect actinorhizal plants exotic to New Zealand. New Zealand Journal of Botany, 35(3):361-367.

Devecchi M, Remotti D, 2004. Effect of salts on ornamental ground covers for green urban areas. Acta Horticulturae, No.643:153-156. http://www.actahort.org

Dommergues Y, Duhoux E, Diem HG, 1999. Les Arbres Fixateurs d'Azote: Caractéristiques Fondamentales et Rôle dans L'aménagement des Écosystèmes Méditerranéens et Tropicaux. Montpellier, France: CIRAD.

Edgin B, Ebinger JE, 2001. Control of autumn olive (Elaeagnus umbellata Thunb.) at Beall Woods Nature Preserve, Illinois, USA. Natural Areas Journal, 21(4):386-388.

Flora of China Editorial Committee, 2008. Flora of China Web. Cambridge, Massachusetts, USA: Harvard University Herbaria. http://flora.huh.harvard.edu/china/

Fukumoto T, Wada T, Muto N, 1995. Purification and identification of Frankia isolated from Elaeagnus pungens root nodules. Japanese Journal of Soil Science and Plant Nutrition, 66(5):490-498.

Hagiladi A, Ben-Jaacov J, Eliasaf A, 1989. Damage caused by wind-borne salts to landscape plants and its prevention by a wind-controlled sprinkler system. Journal of Environmental Horticulture, 7(3):85-87.

Houtman R, 2004. Variegated Trees and Shrubs: The Illustrated Encyclopedia. Cambridge, UK: Timber Press.

Kubus M, 2003. The possibilities for growing trees and shrubs that come from warm climatic regions in the gardens of Szczecin. Dendrobiology, 50:25-28.

Miller JH, 2003. Nonnative invasive plants of southern forests: a field guide for identification and control. General Technical Report - Southern Research Station, USDA Forest Service, No.SRS-62:iv + 93 pp.

Miller JH, Miller KV, 1999. Forest plants of the southeast and their wildlife uses [ed. by Southern Weed Science Society]. USA: University of Georgia Press.

Miller JW, 1997. Plant pathology. Tri-ology Technical Report, 36(6):11-12.

Missouri Botanical Garden, 2008. Flora of China Checklist. USA: Missouri Botanical Garden. http://mobot.mobot.org/W3T/Search/foc.html

Munger GT, 2003. Elaeagnus umbellata. Fire Effects Information System [Online]. USA: USDA-FS. http://www.us/database/feis/plants/shrub/elaumb/all

PIER, 2008. Pacific Islands Ecosystems at Risk. USA: Institute of Pacific Islands Forestry. http://www.hear.org/pier/index.html

Royal Botanic Gardens Sydney, 2008. Australia's Virtual Herbarium. Sydney, Australia: Royal Botanic Gardens. http://avhtas.tmag.tas.gov.au/

Sather N, Eckardt N, 2001. Elaeagnus umbellata, Autumn Olive. Element Stewardship Abstract. Arlington, Virginia, USA: The Nature Conservancy. http://tncweeds.ucdavis.edu/esadocs/documnts/elaeumb.pdf

Tzvelev NN, 2002. On the genera Elaeagnus and Hippophaë (Elaeagnaceae) in Russia and adjacent states. Botanicheskii Zhurnal, 87(11):74-86.

US Fish and Wildlife Service, 1996. In: Technical/Agency Draft Recovery Plan for fringed campion, Silene polypetala (Walt.) Fern. & Schub. US Fish and Wildlife Service, 32 pp.

USDA-ARS, 2008. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx

USDA-NRCS, 2008. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/

Zheng H, Wu Y, Ding J, Binion D, Fu W, Reardon R, 2006. Invasive plants of Asian origin established in the US and their natural enemies. Volume 1. Chinese Academy of Sciences and USDA Forest Service. http:\\www.us/foresthealth/technology/pdfs/IPAOv1ed2.pdf

Links to Websites

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Contributors

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29/02/08 Original text by:

Nick Pasiecznik, Consultant, France

Distribution Maps

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