Elaeagnus umbellata is a species of flowering plant known as Japanese silverberry,[2]umbellata oleaster,[3]autumn olive,[2][4]autumn elaeagnus,[4]spreading oleaster,[4]autumnberry, or autumn berry. 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 colonizebarren land, becoming invasive in the central and northeastern United States and parts of Europe.[5]
Elaeagnus umbellata grows as a deciduousshrub or small tree, typically up to 3.5 metres (11ft) tall, with a dense crown.[5][6] It commonly bears sharp thorns in the form of spur branches.[6] Flowers are fragrant, occur in clusters of white to yellow, are 8–9mm in length and 7mm in diameter, and have four lobes.[5][6]
The leaves are alternate, 4–10cm long and 2–4cm wide, with wavy margins. The leaves are covered with minute silvery scales when they emerge early in the spring[6] 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.[5]
Flowers
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 1cm long.[5] They are an important source of nectar for pollinators such as bees.[7]
Fruit
Microscopic image of leaf cross-section.
The fruit is a small round drupe0.65 to 0.85 centimetres (1⁄4 to 3⁄8in) in diameter.[8] 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, 3–9mm in length, 5mm in diameter, and average 137 milligrams in weight, with a thin skin covering the whole fruit.[5][6] 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.[9] When mature, the red berries contain carotenoids, including considerable amounts of lycopene.[9]
Anatomy of Elaeagnus Umbellata
Leaves
The leaves of a typical Autumn Olive plant are around 2-4 inches long anf arranged in an alternate arrangement along the stem, meaning they are not directly opposite of each other they are staggered. They are smooth and leathery, with their front side being a dull green color, and the backside being a silvery white. This silvery and lightly colored underside make the pant noticeable in the wind and in direct sunlight. The veins of the leaf have a prominent central vein with branching veins stemming from that, helpimg giving the leaf an oval shape with pointed tips at the ends.
Leaf cross - section
The epidermis, also known as the adaxial surface, is the outermost layer of cells that is visible in the background tissue of the image. It is made of a single layer of cells, covered by a way cuticle, it is the protective layer of the leaf. The epidermis functions to reduce water loss via transpiration and provide protection from pathogens and damage. It protects photosynthetic tissues. The trichomes, also known as leaf hairs, are usually located on both upper and lower epidermis of the leaf. They are hair-like structures made of epidermal cells. They function to reduce water loss by creating a slightly humid layer over the leaf surface. They reflect excess sunlight to protect the mesophyll cells. They also deter herbivores to reduce leaf deterioration. In Elaeagnus umbellata, trichomes help the plant survive in dry, sunny, or exposed habitats, making it an extremely resilient plant and contributing to its invasiveness.
Microscopic image of stem cross section.
Stem
The stem is composed of many shoots extending outwards from the perpendicular stem. The stems of a typical Autumn Olive plant are woody and slender, slivery and brownish gray. The stems have this color due to lepidote scales, which are scales located on the stem that give rise to the speckled appearance. The stems are smoother on younger plants and rougher and bushier on older plants. Especially the young sems bear short thorns that extend from the stem about 2 inches long. The typical stem shape is zig-zag and helps give the bushy/rounder dense appearance.
Stem Cross-Section
The outermost single layer of cells that covers the stem is the epidermis. It has a waxy cuticle with little porosity that serves to protect against water and mineral loss and pathogen invasion. In the Autumn Olive plant it helps the plant withstand dry and variable autumn climates. The cortex is the region immediately beneath the epidermis and is composed of parenchyma and collenchyma cells, which provide support. The cortex stores nutrients for the plant’s growth, and in Autumn Olives stores carbohydrates for the plant to survive colder seasons. The Endodermis is the innermost layer of the cortex and contains the Casparian Strip, which blocks the flow of water. The pericycle is a thin layer inside the endodermis that contributes to meristematic cell division. It gives rise to lateral roots and vascular cambium. It allows for stem to grow stronger and thicker. The vascular cylinder, the stele, is the central part of the stem which makes up the xylem, phloem, and pith. The stele is the main transport system for water and minerals throughout the plant. The xylem and phloem are parts of the vascular cylinder. The xylem is crucial for delivering water supply, and the phloem is responsible for delivering sugars and nutrients to plant organs for fruit development and metabolic processes.
Naturalization
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.[5] In the early 19th century, E.umbellata was purposely introduced to the U.S. and the United Kingdom for shelter belts, erosion control, wasteland reclamation, wildlife habitat, and for gardens as an ornamental.[5] By the late 20th century, the shrub became a noxious weed and invasive species in many U.S. states from the east coast to the central prairies, and spread widely across Europe.[5]
The fruit of a Japanese Silverberry plant.
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.[5] 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,[10] it has been planted for wildlife management in parts of the U.S.[5]
In Europe, E. umbellata has spread to the UK, Belgium, France, and Italy, but has been cultivated in the Netherlands and Scotland.[5] In some parts of North America where it has become naturalized, E.umbellata is considered a noxious weed, particularly in the central and northeastern U.S.[5][2] In Canada, it is a "prohibited noxious weed" under the Alberta Weed Control Act 2010.[11]
Because it fixes atmospheric nitrogen in its roots, E.umbellata may grow vigorously and sometimes competitively in infertile soils.[5][12] 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%.[13] However, its ability to change soil chemistry can severely alter or destroy native plant communities.[14]
↑ Dirr, M. 1998. Manual of woody landscape plants: their identification, ornamental characteristics, culture, propagation and uses. Stipes, Champaign, Ill.
1 2 Ingrid M. Fordham; Richard H. Zimmerman; Beverly M. Clevidence; Brent L. Black; Eugene R. Wiley (1998). "Autumn Olive: A Potential Alternative Crop". US Department of Agriculture. Archived from the original on 28 July 2019. Retrieved 10 February 2018.
↑ "Prohibited Noxious Weeds"(PDF). Alberta Weed Control Act, Government of Alberta. 2012. Archived from the original(PDF) on 5 July 2016. Retrieved 8 February 2018.
↑ J.R. Clark, G.E. Hemery, and P.S. Savill. Early growth and form of common walnut (Juglans regia L.) in mixture with tree and shrub nurse species in southern England. Forestry (2008) 81 (5): 631-644 first published online September 5, 2008 doi:10.1093/forestry/cpn036
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