Elaeagnus angustifolia (Russian olive).
Authors: Weyl Philip , Pasiecznik Nick 
Published: March 2021

Abstract

E. angustifolia is a tall shrub (up to 15 m and 1 m d.b.h.), with a dense, rounded crown, native to Europe and Asia and an important deciduous species of arid and semi-arid areas of northwestern China. It was introduced into the USA in the early 1900s, and has now become extensively naturalized in riparian areas of western states bordered on the east by North and South Dakota, Nebraska, Kansas, Oklahoma and Texas (Olson and Knopf, 1986a, 1986b; Shafroth et al., 1995). It also occurs in southern Canada from Ontario to British Columbia. It grows in some eastern USA states, but is not naturalized (Tesky, 1992). This fast-growing (up to 1.8 m per year), nitrogen-fixing species has silver-grey leaves with entire margins (4.5-9 cm), olive-shaped fruit and long thorns. The branches are flexible, pubescent (grey and scaly) and often have a short thorn at the end. The bark is brown, thin with shallow fissures, peeling in long strips. It has a deep taproot and well-developed lateral root system. The small, yellow flowers occur in late spring and have a distinctive spicy aroma. Trees produce seed after 3-5 years, with birds and small mammals dispersing them in their droppings. The seeds can remain viable for up to 3 years and are capable of germinating over a broad range of soil types (Knopf and Olson, 1984). Germination is enhanced by stratification in moist sand for 90 days at 41°C (Vines, 1960). E. angustifolia is found in a range of environments as it is tolerant of drought and saline, alkaline or infertile soils (Vines, 1960; Olson and Knopf, 1986a, 1986b), and has a well-developed root system. It is commonly found growing along floodplains, river banks, stream courses, marshes and irrigation ditches in the western states of the USA, and in desert or dry (150 mm annual rainfall) areas of Western Asia. It bears few fruits if the annual precipitation is >400 mm and also grows slowly if the water table is below 4 m. E. angustifolia is mainly established from seed, although cuttings are used in areas with sufficient moisture. It is relatively shade-tolerant once established and can withstand competition from other shrubs and trees, and can become a dominant climax species, replacing native cottonwoods and willows along water courses in the USA. E. angustifolia has been widely planted in shelterbelts, windbreaks or protective plantings as it is hardy, adaptable to a wide range of soil and moisture conditions and has a dense growth form (Brothers, 1988). It has also been used to revegetate land contaminated by paper mill wastewater (Wagner et al., 1994), potassium (Heinze and Liebmann, 1998) and bentonite (Uresk and Yamamoto, 1994), mine spoilings and as a bioindicator of heavy metal pollution (Aksoy and Sahin, 1999). The timber is hard and brownish-yellow with a beautiful grain, being similar to that of white elm (Ulmus pumila, U. americana). It can be used to make farm tools, furniture and for mining poles and civil construction. The fruits and leaves are valuable for food and animal fodder, whilst the tree is considered a good source for bee foraging. The leaves, shoots, flowers, fruits and bark have been traditionally used in Chinese medicine.