A-7 Gilgit: cult., R.R. Stewart s.n., p.p. (RAW); C-6 Kurram: Parachinar, R.R. Stewart 28038 (RAW).
Autumn-olive is ranked as a "severe threat" (exotic plant species that possess characteristics of invasive species and spread easily into native plant communities and displace native vegetation) by the Tennessee Exotic Pest Plant Council [54]. It is also ranked as a "severe threat" (exotic plant species which possess characteristics of invasive species and spread easily into native plant communities and displace native vegetation; includes species which are or could become widespread in Kentucky) by the Kentucky Exotic Pest Plant Council [30].
Autumn-olive is listed among the top 10 exotic pest plants in Georgia [17], and among "highly invasive species" (species that may disrupt ecosystem processes and cause major alterations in plant community composition and structure and that establish readily in natural systems and spread rapidly) by the Virginia Department of Conservation and Recreation [69]. It is listed as a Category II exotic plant species (considered to have the potential to displace native plants either on a localized or widespread scale) by the Vermont Agency of Natural Resources and The Nature Conservancy of Vermont [68], and as a noxious weed in several West Virginia counties [64].
U.S. Forest Service Region 8 (Southern Region) lists autumn-olive as a category 1 weed (exotic plant species that are known to be invasive and persistent throughout all or most of their range within the Southern Region and that can spread into and persist in native plant communities and displace native plant species and therefore pose a demonstrable threat to the integrity of the natural plant communities in the Region). The introduction of Category 1 Species is prohibited on National Forest System Lands [65].
The following description provides characteristics of autumn-olive that may be relevant to fire ecology and is not meant to be used for identification. Keys for identifying autumn-olive are available (e.g. [5,18,38,46,51,71,77]). Photos and descriptions of autumn-olive are also available online at the Invasive.org and Invasive Plant Atlas of New England websites.
Autumn-olive is a many-branched, deciduous shrub or shrubby tree, growing 10 to16 feet (3-5 m) tall [5,14,18,19,46,77]. Leaves are alternate [5,18,19,46,51,57], simple [19,46], and variable in size [19], ranging from 0.4 to 3 inches (1-8 cm) long and 0.4 to 1.6 inches (1-4 cm) wide [5,46,51]. Thorns several inches in length are formed on spur branches [55]. Autumn-olive fruits are single-seeded drupes, 0.2 to 0.4 inches (4-10 mm) in diameter, produced on pedicels [14,18,19,38,46,51,57].
Autumn-olive forms root nodules induced by symbiosis with actinomycetes in the soil. This symbiosis permits the fixation and subsequent utilization of atmospheric nitrogen [42,61,71].
The biology and ecology of autumn-olive are not well-studied in North America. More research is needed to better understand autumn-olive's key biological traits, habitat requirements and limitations, and interactions with native North American flora and fauna.
Autumn-olive occurs throughout the eastern United States, from Maine, west to Wisconsin, Iowa, Nebraska, Kansas, Arkansas, and Louisiana, and south into Florida [5,9,26,27,36,38,46,51,57,63,71,75,77,78]. It also occurs in southern and eastern Ontario [4] and Hawaii [73]. Kartesz and Meacham [29] recognize E. umbellata var. parvifolia, with the same distribution as autumn-olive.
Northern distribution of invasive autumn-olive populations in North America may be limited by cold intolerance from USDA climate zone 5 north [55], although one cultivar has been described as "hardy" to zone 6 [25]. Autumn-olive is native to Asia and was introduced to North America around 1830 [5,19,51,57,65,71,77].
The following biogeographic classification systems demonstrate where autumn-olive could potentially be found based on floras and other literature, herbarium samples, and confirmed observations. Predicting distribution of nonnative species is difficult due to gaps in understanding of their biological and ecological characteristics, and because they may still be expanding their range. These lists are speculative and may not be accurately restrictive or complete.
Information about autumn-olive and fire is lacking. Research that examines the interactions of fire and autumn-olive, the effects these interactions may have on native communities and ecosystems and their respective FIRE REGIMES is needed.
Fire adaptations: As of this writing (2003) there is no published information describing adaptations of autumn-olive to fire. It is likely, though speculative, that autumn-olive generally responds to fire damage by sprouting (see Asexual regeneration). Russian-olive (E. angustifolia), another introduced and invasive Elaeagnus in North America, sprouts from the root crown following fire (see FEIS botanical and ecological summary for Russian-olive).
FIRE REGIMES: The following table lists fire return intervals for communities or ecosystems throughout North America where autumn-olive may occur. This list is presented as a guideline to illustrate historic FIRE REGIMES and is not to be interpreted as a strict description of FIRE REGIMES for autumn-olive. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Community or Ecosystem Dominant Species Fire Return Interval Range (years) maple-beech-birch Acer-Fagus-Betula > 1,000 silver maple-American elm A. saccharinum-Ulmus americana < 35 to 200 sugar maple A. saccharum > 1,000 sugar maple-basswood A. saccharum-Tilia americana > 1,000 [72] bluestem prairie Andropogon gerardii var. gerardii-Schizachyrium scoparium 33,43] Nebraska sandhills prairie A. gerardii var. paucipilus-Schizachyrium scoparium < 10 bluestem-Sacahuista prairie A. littoralis-Spartina spartinae 43] plains grasslands Bouteloua spp. < 35 blue grama-buffalo grass B. gracilis-Buchloe dactyloides 43,76] sugarberry-America elm-green ash Celtis laevigata-Ulmus americana-Fraxinus pennsylvanica < 35 to 200 Atlantic white-cedar Chamaecyparis thyoides 35 to > 200 [72] northern cordgrass prairie Distichlis spicata-Spartina spp. 1-3 [43] beech-sugar maple Fagus spp.-Acer saccharum > 1,000 black ash Fraxinus nigra 72] cedar glades Juniperus virginiana 3-7 [43] yellow-poplar Liriodendron tulipifera 72] wheatgrass plains grasslands Pascopyrum smithii 43,45,76] Great Lakes spruce-fir Picea-Abies spp. 35 to > 200 northeastern spruce-fir Picea-Abies spp. 35-200 [7] southeastern spruce-fir Picea-Abies spp. 35 to > 200 [72] red spruce* P. rubens 35-200 jack pine Pinus banksiana 7] shortleaf pine P. echinata 2-15 shortleaf pine-oak P. echinata-Quercus spp. < 10 slash pine P. elliottii 3-8 slash pine-hardwood P. elliottii-variable < 35 sand pine P. elliottii var. elliottii 25-45 [72] longleaf-slash pine P. palustris-P. elliottii 1-4 [39,72] longleaf pine-scrub oak P. palustris-Quercus spp. 6-10 Table Mountain pine P. pungens 72] red pine (Great Lakes region) P. resinosa 10-200 (10**) [7,15] red-white-jack pine* P. resinosa-P. strobus-P. banksiana 10-300 [7,21] pitch pine P. rigida 6-25 [3,22] pocosin P. serotina 3-8 eastern white pine P. strobus 35-200 eastern white pine-eastern hemlock P. strobus-Tsuga canadensis 35-200 eastern white pine-northern red oak-red maple P. strobus-Q. rubra-Acer rubrum 35-200 loblolly pine P. taeda 3-8 loblolly-shortleaf pine P. taeda-P. echinata 10 to < 35 Virginia pine P. virginiana 10 to < 35 Virginia pine-oak P. virginiana-Quercus spp. 10 to < 35 sycamore-sweetgum-American elm Platanus occidentalis-Liquidambar styraciflua-U. americana 72] eastern cottonwood Populus deltoides 43] aspen-birch P. tremuloides-Betula papyrifera 35-200 [7,72] black cherry-sugar maple Prunus serotina-A. saccharum > 1,000 oak-hickory Quercus-Carya spp. < 35 northeastern oak-pine Quercus-Pinus spp. 10 to < 35 southeastern oak-pine Quercus-Pinus spp. < 10 white oak-black oak-northern red oak Q. alba-Q. velutina-Q. rubra < 35 northern pin oak Q. ellipsoidalis < 35 bear oak Q. ilicifolia < 35 bur oak Q. macrocarpa 72] oak savanna Q. macrocarpa/Andropogon gerardii-Schizachyrium scoparium 2-14 [43,72] chestnut oak Q. prinus 3-8 northern red oak Q. rubra 10 to < 35 post oak-blackjack oak Q. stellata-Q. marilandica < 10 black oak Q. velutina < 35 live oak Q. virginiana 10 to72] cabbage palmetto-slash pine Sabal palmetto-P. elliottii 39,72] little bluestem-grama prairie Schizachyrium scoparium-Bouteloua spp. 43] eastern hemlock-yellow birch T. canadensis-Betula alleghaniensis > 200 [72] elm-ash-cottonwood Ulmus-Fraxinus-Populus spp. 7,72] *fire return interval varies widely; trends in variation are noted in the species summaryAs of this writing (2003) it is unclear what impacts fire might have on invasive populations of autumn-olive or on communities where autumn-olive is invasive. Research is needed to determine the immediate effects of fire on autumn-olive, its ability to survive 1 or more fires, and its relative competitiveness in postfire communities.
It appears that autumn-olive will sprout in response to damage from fire, indicating a single burn is probably not sufficient to eradicate it [37,53,59]. It is unclear how effective multiple prescribed burns might be for controlling invasive autumn-olive. While a single fire is unlikely to eradicate autumn-olive, periodic burning might control its spread and eventually reduce its presence. Any management activity that removes aboveground tissue, prevents seed production, and depletes energy reserves is likely to reduce autumn-olive invasiveness, especially when conducted persistently.
Postfire colonization via nearby seed sources seems likely (see Seed dispersal), provided there is enough light for seedling establishment in the postfire environment. However, more information is needed describing seedbed requirements for autumn-olive seed germination and seedling establishment.
Apart from questions about effectiveness of prescribed fire as an autumn-olive control measure, use of fire in areas where autumn-olive is present may or may not be appropriate, depending on management goals and the particular ecosystem involved. Using fire to control autumn-olive in habitats where fire is infrequent may do substantial damage to fire-intolerant native species. Conversely, fire may be appropriate where management goals include maintaining native seral species or otherwise enhancing ecosystem structure and function through use of prescribed fire. For more information regarding fire effects on native flora, see the appropriate FEIS species summaries on this website.
Autumn-olive has been planted throughout much of eastern North America for various purposes (Management Considerations), and has subsequently escaped into a variety of natural and seminatural habitats [4,10,40,71]. For example, Invasive Plant Atlas of New England [37] lists the following general habitats where autumn-olive may be found in New England: abandoned field, abandoned gravel pit, early-successional forest, edge, pasture, planted forest, railroad right-of-way, roadside, utility right-of-way, vacant lot, yard, or garden. It is probably most prolific on disturbed or ruderal sites [5,8,26,40,77].
Autumn-olive grows best on deep, relatively coarse-textured soils that are moderately-well to well drained [1,65]. It does less well on very dry soil and usually fails on very shallow, poorly drained, or excessively wet soil. Autumn-olive does not require highly fertile soil, and it appears to thrive equally well on soils ranging from "moderately acid to moderately alkaline" [1]. In Ontario, escaped autumn-olive is found in a variety of dry to mesic sandy, forested and open to sparsely shaded habitats, with soil pH from 5-7. It is most invasive in areas of dry sandy soils. Although it has been cultivated on fine-textured, periodically wet soils, it is generally not invasive on such sites in southern Ontario [4].
Impacts: In general, invasive autumn-olive impacts native biotic communities in eastern North America by displacing native plants. Invasive populations can supplant native habitat, sometimes forming dense thickets. Prodigious seed production and widespread seed dispersal by frugivorous birds probably contribute to its invasiveness [55]. An Illinois study reported autumn-olive concentrations of 5,225 stems per hectare in a pine plantation, 27,500 stems per hectare in a grazed upland woods, and 33,975 stems per hectare in hardwood-dominated ravines [10]. Autumn-olive densities of 125,000 plants hectare were recorded in the understory of a yellow-poplar-sweetgum plantation in southwestern Indiana in 2000. This population was established from nearby plantings in the early 1970's. Although 90% of these individuals were 2 feet (0.6 m) or less in height, they formed "a nearly impenetrable thicket" and were "commonly the only understory species present" [11].
Nestleroad and others [40] have suggested that impacts of invasive autumn-olive may be greatest in communities adapted to infertile soils, where its nitrogen-fixing capabilities might confer substantial competitive advantage against native species. It is conceivable that autumn-olive could alter the nitrogen cycle in "infertility-dependent" natural communities, shifting the potential native community on these sites. Nestleroad and others [40] expressed concern that natural communities of sandy, infertile habitats in southern and eastern Ontario, and throughout the Great Lakes region, are already seriously impacted by other pressures.
Control: Controlling invasive autumn-olive may require frequent monitoring and repeated treatments to achieve success. Because seeds can be dispersed long distances by birds, it is helpful to eradicate autumn-olive populations in areas surrounding the threatened area, when possible. If the infested area is large, or if eradication of surrounding populations is not feasible, land managers may wish to focus control efforts in the most ecologically significant and/or least invaded areas first. In closed-canopy forests, control can likely be achieved through routine monitoring and eradication of new individuals by hand pulling or spot-spraying with herbicide [11].
Prevention: Where appropriate, maintaining dense, frequently mowed grass or other dense native vegetation can help prevent establishment of autumn-olive seedlings [40].
Integrated management: No information
Physical/mechanical: Hand pulling young seedlings and sprouts can be effective, particularly from moist soil [53,59]. Seedlings are easiest to identify in early spring because autumn-olive produces leaves earlier than most native shrubs [55,59]. Mowed or cut plants reportedly "resprout vigorously" [53,59], so these methods alone will probably not effectively control mature plants. Even repeated cutting is apparently ineffective without treating stumps and/or resprouts with herbicide [53]. Treating cut surfaces with glyphosate is an effective control measure and can minimize negative impacts on native vegetation when carefully applied (see Chemical control) [53,59].
Fire: See Fire Management Considerations.
Biological: No information
Chemical: Several herbicides have been used alone or in combination to provide effective control of autumn-olive, including glyphosate, triclopyr, 2,4-D, and dicamba. This is not intended as an exhaustive review of chemical control methods. For more information regarding appropriate use of herbicides against invasive plant species in natural areas, see The Nature Conservancy's Weed control methods handbook. For more information specific to herbicide use against autumn-olive, see The Nature Conservancy's Element Stewardship abstract of autumn-olive and the Connecticut Invasive Plant Working Group (CIPWG) and Illinois Nature Preserves Commission websites.
Dicamba and 2,4-D have been used as a foliar application to effectively control autumn-olive [35,53,59]. Triclopyr has also been used effectively on resprouts following cutting [53]. Because this method is conducted during the growing season, and because 100% coverage of foliage is recommended for most effective control, Szafoni [59] suggests that foliar application is best suited to shorter plants.
For larger plants, basal-bark application of triclopyr or 2,4-D can control invasive autumn-olive [11,35,53]. Basal-bark treatment is the application of herbicide solution directly to the bark the lower portion of woody plants. Herbicide then penetrates the bark and is absorbed by the plant [53]. Rather than a broad band application, a thin line of herbicide applied around the entire circumference of the stem 6-12 inches (15-30 cm) above the ground is sufficient, and less likely to harm nearby, desirable plants [53,59].
Direct application of glyphosate to cut stumps can also be effective, particularly late in the growing season (July-September) [53,59]. According to Szafoni [59], reduced application rates of 10-20% solution (compared with 50-100% recommended on some glyphosate product labels) are sufficient for effective treatment of cut stems. Careful application of herbicide directly to target plants can reduce damage to nearby, desirable vegetation [59].
Multiple herbicide treatments may be required to completely kill all plants. Edgin and Ebinger [11] describe treating an invasive population of autumn-olive in Illinois with basal-bark applications of triclopyr during springs of 1996 and 1997. A subsequent search in early summer 1997 yielded no evidence of live autumn-olive in treated areas. But by 2000, autumn-olive had re-established within these same treated areas. Because a dense population of well-established autumn-olive remained in an area adjacent to treatment plots, many of the newly established plants were assumed to have originated from the seed bank or from seeds transported into the plots by birds after herbicide treatments. But nearly 11% of the larger stems (2.6 to 4.9 feet (80-150 cm) tall) had an "enlarged basal caudex" and were considered to be resprouts that were only top-killed by the herbicide treatment.
Cultural: No information
Autumn-olive has been promoted as a beneficial wildlife species and planted in wildlife management areas in the eastern U.S. to provide food and cover [8,9,10,14,20,23]. Fruit remains on the plant until late winter (see Seasonal Development), potentially becoming an important wildlife food during periods of seasonal food scarcity [14]. Fruits are consumed by a variety of wildlife, including songbirds, northern bobwhite, ruffed grouse, mourning doves, ring-necked pheasants, wild turkeys, mallards, raccoons, skunks, opossums, and black bears [1,23,57]. Songbirds that eat autumn-olive fruit include: gray catbirds, hermit thrushes, wood thrushes, house finches, American robins, cardinals, cedar waxwings, common grackles, evening grosbeaks, fox sparrows, house sparrows, song sparrows, white-throated sparrows, mockingbirds, myrtle warblers, purple finches, rufous-sided towhees, starlings, tree swallows, and veerys [1,40,58]. Autumn-olive is also browsed by white-tailed deer [65].
Palatability/nutritional value: No information
Cover value: Autumn-olive provides cover for wildlife, especially songbirds, game birds, and rabbits [65].
Autumn-olive is found across many habitats in North America
(see Site Characteristics),
and may be associated with a variety of plant taxa, functional guilds and communities.
As of this writing (2003), there is very little published information concerning
habitat types and plant communities where autumn-olive might invade.
Autumn-olive is not a climax dominant or indicator species in habitat type classifications.
Catling et al. [4] described the following habitats in southern and
eastern Ontario where escaped autumn-olive was found most frequently: deciduous
and mixed forests dominated by black oak (Quercus velutina), white oak (Q.
alba), eastern white pine (Pinus strobus), and red maple (Acer rubrum);
eastern redcedar (Juniperus virginiana) glades; prairie/savanna relicts dominated by
indiangrass (Sorghastrum nutans); coniferous plantations; seasonally wet,
"open floodplain thickets;" gravelly till in northern white-cedar
(Thuja occidentalis) floodplain slope woodland; raised sandy
knolls in open to sparsely shaded graminoid fens; and low sand dunes in eastern cottonwood
(Populus deltoides) savanna.
Autumn-olive has been promoted for reclamation of mine spoils and other disturbed soils [1,13]. It has been planted for reclamation of surface coal mine sites because it is tolerant of low pH soil conditions often found on these sites [14,23,68]. It has also been suggested for use in stabilizing eroded soils in exposed coastal areas due to its salt spray tolerance [60]. An additional benefit to planting autumn-olive in these and other situations, where reclamation of disturbed and frequently nutrient-poor soils is an important objective, is its ability to fix atmospheric nitrogen [13,60].
Autumn-olive has been a recommended species for planting as a tall shrub component in windbreaks in the Great Plains, in part due to its wildlife food and cover value [20,65].
Autumn-olive is used in plantations for companion planting with black walnut to enhance black walnut productivity. It is thought autumn-olive enhances black walnut growth by increasing ecosystem nitrogen pools through nitrogen fixation and by decreasing herbaceous competition [44,49,50,61,69]. Field experiments have demonstrated that interplanting autumn-olive with black walnut can increase seasonal soil nitrogen mineralization rates [42], significantly (p < 0.01) increase black walnut leaf nitrogen concentration [70], and substantially improve black walnut growth and yield [6,42,44,44,70], compared with growing black walnut alone. Interplanting autumn-olive may also indirectly enhance black walnut growth and yield by reducing incidence of leaf fungal diseases through interactions with fungivorous microarthropods in the litter layer [31,32]. White ash (Fraxinus americana) growth and yield also increases when interplanted with autumn olive [44].
The following table describes approximate flowering times reported from a variety of North American locations:
February March April May June Northeastern U.S. [18] X X New England [37] X X Illinois [38] X X Florida [5] X X X Blue Ridge Mountains [75] X X West Virginia [57] X X North & South Carolina [46] X XIn the central and southern Appalachian regions, autumn-olive fruit ripens in August and September [46,57]. Fruit generally remains on the plant until late winter [14]. Autumn-olive generally produces leaves in early spring, prior to most native plants [55,59].
As of this writing (2003) there is very little published information describing regeneration biology in autumn-olive. Research is needed to determine the precise nature of asexual regeneration, conditions that promote or constrain seedling establishment and early growth, and the role of soil-stored seed in autumn-olive invasiveness.
Breeding system: Elaeagnus spp. are polygamodioecious [5,19,41,74].
Pollination: Autumn-olive is open-pollinated [65], often by insects [41].
Seed production: Mature plants can produce about 30 pounds (14 kg) of fruit annually. Thirty pounds of fruit is generally equivalent to about 3 pounds (1.4 kg) of seed, or about 66,000 seeds [65]. Under favorable conditions, autumn-olive can produce fruit by 3 to 5 years of age, usually at about 4 to 8 feet (1.2-2.4 m) in height. Fruit production is reduced by shading [1].
Seed dispersal: Seeds are dispersed by frugivorous birds and, to a lesser extent, small mammals [11,37,40].
Seed banking: No information
Germination: Autumn-olive seed germination is enhanced by a period of cold stratification. Fowler and Fowler [14] determined germination rates for unstratified seeds were significantly (p<0.05) lower than those receiving 8 or more weeks of cold stratification at 41 degrees Fahrenheit (5 °C). Optimal conditions for autumn-olive germination were 16-20 weeks of cold stratification followed by 2 weeks of night/day temperatures of 50/62 degrees Fahrenheit (10/20). These conditions resulted in >90% germination.
However, cold stratification is not a prerequisite for germination. Fowler and Fowler [14] found 51% of unstratified seeds germinated after 10 weeks of night/day temperatures of 50/62 degrees Fahrenheit (10/20 °C). Jinks and Ciccarese [28] found that >70% of seeds from their "control" group germinated after 8 weeks despite receiving no cold temperature treatment.
Seedling establishment/growth: No information
Asexual regeneration: Solecki [53] and Szafoni [59] indicated burned, mowed, and cut plants "resprout vigorously." The Invasive Plant Atlas of New England website [37] reports that if autumn olive is cut, "it resprouts abundantly," and burning only results in resprouting "from the stump." Russian-olive (E. angustifolia), another introduced and invasive Elaeagnus in North America, sprouts from the root crown and sends up root suckers (see FEIS botanical and ecological summary for Russian-olive).
Autumn-olive appears best adapted to early-successional habitats in North America. It has been called "moderately" shade tolerant [1], but is thought to be generally absent from areas with very low light intensity, such as under a dense forest canopy [40]. Edgin and Ebinger [11] noted autumn-olive plants were restricted to "open canopy areas" within the interior of an "old-growth" forest along the Wabash River in southwestern Indiana. Based on this observation, they suggested autumn-olive is "not well adapted to low-light conditions."
The possibility of autumn-olive invasion in forested habitats should not be precluded on the basis of successional status. Ebinger and Lehnen [10] describe the following habitats in east-central Illinois where autumn-olive has invaded from nearby plantings: 1) a small plantation of pines (Pinus spp.), 3.3 to 6.6 feet (1-2 m) tall; 2) small ravines in the "early tree stage of succession," containing "scattered individuals" of black walnut (Juglans nigra), prairie crabapple (Malus ioensis), shingle oak (Quercus imbricaria), northern red oak (Q. rubra), black cherry (Prunus serotina), and American elm (Ulmus americana), mostly less than 4 inches (10 cm) dbh; 3) a grazed upland forest dominated by white oak, mostly between 12 and 20 inches (30-50 cm) dbh. Data from sample plots (see table below) indicate autumn-olive stems were numerous within these sites, with a substantial proportion of plants greater than 20 inches (50 cm) tall. While it is difficult to draw firm conclusions from these and previous site descriptions without more detailed information, it appears autumn-olive has at least some ability to establish under a forest canopy.
Habitat autumn-olive density (stems/ha) proportion autumn-olive plants >20 inches tall pine plantation 5,225 30% hardwood ravine 33,975 20% oak (Quercus spp.) forest 67,925 7% Data adapted from Ebinger and Lehnen [10].The currently accepted scientific name for autumn-olive is Elaeagnus
umbellata Thunb. (Elaeagnaceae) [5,18,19,29,38,46,48,51,57,71,75,77].
Kartesz and Meacham [29] recognize the variety Elaeagnus umbellata Thunb.
var. parvifolia (Royle) Schneid.
Several cultivars have been developed by the U.S. Department of Agriculture,
Soil Conservation Service, and distributed for wildlife and other conservation uses
(see Importance To Livestock And Wildlife)
[1,8,10,23,25,65].
Elaeagnus umbellata is known as Japanese silverberry,[1] umbellata oleaster,[2] autumn olive,[1][3] autumn elaeagnus,[3] or spreading oleaster.[3] The species is indigenous to eastern Asia and ranges from the Himalayas eastwards to Japan. It is a hardy, aggressive invasive species able to readily colonize barren land, becoming a troublesome plant in the central and northeastern United States and Europe.[4]
Elaeagnus umbellata grows as a deciduous shrub or small tree, typically up to 3.5 metres (11 ft) tall, with a dense crown.[4][5] It commonly bears sharp thorns in the form of spur branches.[5] Flowers are fragrant and occur in clusters of white to yellow, 8–9 mm in length and 7 mm in diameter, and have four lobes.[4][5]
The leaves are alternate, 4–10 cm long and 2–4 cm wide with wavy margins. The leaves are covered with minute silvery scales when they emerge early in spring,[5] but turn greener above as the scales wear off during the summer. The underside is more intensely covered in the silvery scales, differing from the related E. angustifolia, which remains silvery until it sheds its leaves in the fall.[4]
The flowers are borne in the leaf axils in clusters of 1-7. They are pale yellowish-white, fragrant, (often heavily fragrant) and have a four-lobed corolla 1 cm long.[4] They are an important source of nectar for pollinators such as bees.[6]
The fruit is a small round drupe 1/4 to 1/3 inches (0.65 to 0.85 cm) in diameter.[7] The unripe fruit is silvery-scaled and yellow. It ripens to red, dotted with silver or brown. The ripe fruits are pulpy, juicy and sweet, 3–9 mm in length, 5 mm in diameter, and average 137 milligrams in weight, with a thin skin covering the whole fruit.[4][5] Having a sweet and tart flavor, the berries can be eaten fresh or processed for jam, condiments, flavoring, or used as a substitute for tomato.[8] When mature, the red berries contain carotenoids, including considerable amounts of lycopene.[8]
In its origin regions of tropical and temperate Asia, E. umbellata is not considered to be an invasive species, but in many world regions, it has become invasive across wild and cultivated areas, particularly in the eastern United States.[4] In the early 19th century, E. umbellata was purposely introduced to the United States and the United Kingdom for shelter belts, erosion control, wasteland reclamation, wildlife habitat, and for gardens as an ornamental.[4] By the late 20th century, the shrub became a noxious weed and invasive species in many US states from the east coast to the central prairies, and spread widely across Europe.[4]
Due to its substantial seed production and avid germination potential, E. umbellata rapidly invades new areas where it can resprout readily after burning or cutting.[4] Because E. umbellata stands are habitats for wildlife, such as providing forage and shelter for deer, nesting sites for birds, and berries as food for several species,[9] it has been planted for wildlife management in parts of the United States.[4]
In Europe, E. umbellata has spread to the United Kingdom, Belgium, France, and Italy, but has been cultivated in the Netherlands and Scotland.[4] In some parts of North America where it has become naturalized, E. umbellata is considered a noxious weed, particularly in the central and northeastern United States.[4][1] In Canada, it is a "prohibited noxious weed" under the Alberta Weed Control Act 2010.[10]
Because it fixes atmospheric nitrogen in its roots, E. umbellata may grow vigorously and sometimes competitively in infertile soils.[4][11] It can increase available nitrogen in soils and benefit some nearby plants, and when grown in orchards, it can increase yields of adjacent fruit trees up to 10%.[12] However, its ability to change soil chemistry can severely alter or destroy native plant communities.[13]
Leaves
Blossoms
Ripe fruit
Ripe fruit
Leaf upperside
Zoomed view
{{cite web}}: CS1 maint: uses authors parameter (link) Elaeagnus umbellata is known as Japanese silverberry, umbellata oleaster, autumn olive, autumn elaeagnus, or spreading oleaster. The species is indigenous to eastern Asia and ranges from the Himalayas eastwards to Japan. It is a hardy, aggressive invasive species able to readily colonize barren land, becoming a troublesome plant in the central and northeastern United States and Europe.
