Introduced Species Summary Project
Russian Olive
(Elaeagnus angustifolia L.)
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Common Name: Russian olive (also Russian-olive, Russian olive); Oleaster
Scientific
Name: Elaeagnus angustifolia L.
Classification:
Division: Magnoliophyta (angiosperms,
flowering plants)
Class: Magnoliopsida
(dicotyledons)
Order: Rhamnales
Family: Elaeagnaceae
(Oleaster family)
Identification: The
Russian olive is a large, spiny, perennial deciduous shrub or small growing
tree (up to 40ft.) that is usually found in riparian areas, as well as fields
and other open areas. The plant
has elliptical to lanceolate shaped leaves and thorny branches. The leaves are alternate and simple,
about 1 to 3 inches long and ½ inch wide, distinctly scaly on the top and
silvery and scaly on the bottom.
The leaves of the Russian olive are dull green to gray in color. Buds are quite small, round and
silvery-brown in color and covered with many scales. The branches are silvery, scaly and thorny when the plant is
young, and turn a shiny, light brown color when mature. The bark on the Russian olive is at
first smooth and gray, and then becomes unevenly rigid and wrinkled later on.
Its fruit is like a berry, about ½ inch long, and is yellow when young (turning
red when mature), dry and mealy, but sweet and edible. The fruit matures from August to
October and stays on the tree throughout the winter. In mid-summer, from May to June, the Russian olive blooms
fragrant yellow flowers with silvery-gray willow-like leaves, which can cause
it to be easily confused with the willow-leaf pear tree.
Original
Distribution: The Russian
olive is native of temperate western Asia (Afghanistan; Armenia; Azerbaijan;
China; Georgia; Iran; Kazakhstan; Mongolia; Russia; Tajikistan; Turkmenistan;
Uzbekistan); some parts of tropical Asia (northwestern India and northeastern
Pakistan); and southeastern Europe (Belarus; Moldova). The Russian olive was originally
planted in Eurasia as an ornamental tree, and was first cultivated in Germany
in 1736.
Site and Date of Introduction: The Russian olive was
introduced to the central and western United States in the late 1800’s as an
ornamental tree and a windbreak, before spreading into the wild. By the mid 1920’s it became naturalized
in Nevada and Utah, and in Colorado in the 1950’s.
Current Distribution: The Russian olive is found throughout North America,
but mainly in the central and western portions of the United States. After introduction it escaped
cultivation and naturalized in 17 western states from the Dakotas, Nebraska,
Kansas, Oklahoma, and Texas westward to the Pacific coast. It is most abundant in the Great Basin
Desert region and the riparian zones of the Great Plains. The Russian olive is also found on the
east coast of the United States from Pennsylvania to Virginia, and in southern
Canada, from Ontario to British Columbia.
Mode(s) of Introduction: The
Russian olive was purposely introduced by human beings since it is an
attractive, thriving landscape species. Its dense, silvery foliage provides a good hedge or screen
to block out unwanted views. The
plant is quite hardy and grows well near highways in particular. In the 1940’s, the Russian olive was
deliberately planted in the eastern and southern U.S. for revegetation of
disturbed areas and until recently it was transplanted for wildlife planting
and windbreaks by the U.S. Soil Conservation Service.
Reason(s) why it has Become Established: The Russian olive has been extremely successful in the
United States mainly due to its resistance to varying water, soil and
temperature conditions, a proliferation of seed-dispersing birds and its
nitrogen-fixing ability. Birds
foraging on the Russian olive’s fruit scatter seeds at a very rapid rate. As the seeds are ingested along
with the fruit by birds and other small mammals, they are subsequently
scattered in their droppings. The
seeds of the Russian olive are very resilient, enduring the stomach’s digestive
juices, and distributing themselves for up to three years over a broad range of
soil types.
The Russian olive is simply a very adaptive tree and tends
to be an initial colonizer post-disturbance. It is very widespread in riparian zones and is found growing
along floodplains, riverbanks, streams and marshes. The Russian olive can tolerate large amounts of salinity and
can grow well in a variety of soil combinations from sand to heavy clay. It can also survive a unique range of
temperature (from –50 to 115 degrees Fahrenheit) and can tolerate shade well,
allowing it to withstand competition from other trees and shrubs. The Russian olive can also absorb
nitrogen into its roots, thereby having the ability to grow on bare, mineral
surfaces and dominate other riparian vegetation where old growth trees once
survived.
Ecological
Role: The fruit of the Russian olive tree is a great source of
food and nutrients for birds, so while this suggests the plant plays an
important ecological role in birds’ habitat, ecologists have found that bird
species richness is actually greater in areas with a higher concentration of native
vegetation. Over 50 different
species of mammals and birds do eat the fruit, 12 of them being game
birds. Deer and other livestock
feast on the leaves of the Russian olive and beavers use the branches for
constructing dams. The canopy of
the Russian olive provides good thermal cover for some wildlife species. Doves, mocking birds, roadrunners and
other birds use the thick growth of branches as nesting sites.
Benefit(s): The Russian olive is principally
an ornamental. Including the
ecological benefits listed above, the Russian olive and its tremendous
adaptability has allowed it to be planted for erosion control and highway and landscape
enhancement. The branches from the
Russian olive not only provide shade and shelter, but some fuel wood, gum and
resin. The fruit of the Russian
olive can be used as a base in some fruit beverages and the plant has also been
know to be a source of honey. As
previously mentioned, the Russian olives’ nitrogen-fixing ability makes it a
good companion tree by increasing surrounding crops’ yield and growth, however
with its ability to take over very quickly, it is wise to plant another
species.
The Russian olive, with its
tendency to spread quickly, is a menace to riparian woodlands, threatening
strong, native species like cottonwood and willow trees. They are responsible for out competing
a lot of native vegetation, interfering with natural plant succession and
nutrient cycling and choking irrigation canals and marshlands in the western United
States. This displacement of
native plant species and critical wildlife habitats has undoubtedly affected
native birds and other species.
The heavy, dense shade of the Russian olive is also responsible for
blocking out sunlight needed for other trees and plants in fields, open
woodlands and forest edges.
Overall, areas dominated by the Russian olive do not represent a high
concentration of wildlife.
Control Level Diagnosis: The
Russian olive has been categorized as a noxious weed in New Mexico and Utah,
and as an invasive weed by California, Nebraska, Wisconsin and Wyoming state
authorities. There is a serious
concern that should the Russian olive continue to establish itself, it will
become the dominant woody plant along Colorado’s rivers, where it is already
taking over hundreds of thousands of acres of cottonwood and willow
woodlands. Some cities are already
taking steps to remove the Russian olive.
Control Method: The Russian olive is difficult,
if not impossible, to control or eradicate. The main reason for this is the Russian olives’ capability
of producing root crown shoots and “suckers”. Pruning
or simply cutting does not have any effect on the Russian olive, as it tends to
resprout heartily from the root stump. The Russian olive is also a fire resistant plant and tends to
colonize burned areas, yet burning with a combination of herbicide spraying on
the stump can possibly prevent the Russian olive from resprouting. Mowing the Russian olive with a brush
type mower and removing cut material (and then spraying) is probably the most
effective way of attempting to eradicate the plant. There
are two kinds of fungus that can affect the Russian olive: Verticillium wilt and Phomopsis
canker. Verticillium wilt attacks
and usually kills the Russian olive in eastern areas that are very humid and
wet or poorly drained, causing the leaves to wilt. Canker disease is a reddish-brown to black canker that
appears on smaller branches, resulting in a kind of “bleeding” on the diseased
areas. Once the fungus covers the
branch, lack of water causes the leaves to wilt and the branches die off. Although the Russian olive can thrive
without water, it becomes stressed when there is a severe lack of water,
causing the fungus to appear.
Finally, few animals and insects feed or bother the Russian olive, so
there tends to be no effective biological control.
References:
1. Haber,
Erich. Russian-olive –
Oleaster. Elaeagnus angustifolia
L. Oleaster Family – Elaeagnaceae. Invasive Exotic Plants of Canada Fact Sheet
No. 14. National Botanical
Services, Ottawa, ON, Canada.
April 1999.
2. Muzika,
Rose-Marie, U.S. Forest Service, Morgantown, WV and Jil M. Swearingen, U.S.
National Park Service, Washington, DC. “Weeds Gone Wild” Plant Conservation
Alliance, Alien Plant Working Group. August 1997 http://www.nps.gov/plants/alien/fact/elan1.htm
3. National
Invasive Species Council. U.S.
Department of the Interior – South.
National Agricultural Library of the U.S. Department of
Agriculture. Washington, D.C. Dec.
19, 2001. http://www.invasivespecies.gov/profiles/russolive.shtml
4. USDA, ARS,
National Genetic Resources Program. Germplasm Resources Information Network -
(GRIN). [Online Database] National Germplasm Resources Laboratory, Beltsville,
Maryland. http://www.ars-grin.gov/var/apache/cgi-bin/npgs/html/taxon.pl?14915
5.
USDA, NRCS. 2001. The PLANTS Database, Version 3.1
National Plant Data Center, Baton Rouge, LA. http://plants.usda.gov/cgi_bin/plant_profile.cgi?symbol=ELAN&photoID=elan_1v.jpg#links
6. U.S.
Department of Agriculture, Forest Service, Rocky Mountain Research Station,
Fire Sciences Laboratory (2002, February). Fire Effects Information
System. http://www.fs.fed.us/database/feis/plants/tree/elaang/index.html
Author: Emily Collins
Last Edited: March 6, 2002
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Project Editor: James A. Danoff-Burg, Columbia University