Autumn Olive is a multi-branched woody deciduous shrub in the Elaeagnaceae family. It can grow up to a height of 6 m and a width of 9 m. It has simple, elliptically shaped leaves with smooth, wavy edges, arranged alternately on the branches. The underside of its leaves features distinct silver scales and small, golden-brown spots. From May to June, it produces cream-coloured, 4-10 mm long flowers with four petals and stamens. It produces small (3-9 mm) red fleshy berries with silver scales when mature. Berries can be seen as early as August, with them ripening by September to October.
Part of what makes Autumn Olive such an effective invasive species is that it can tolerate and grow in a wide range of soils with varying acidity and salinity levels. As a result, it is found in a variety of habitats. It is best suited for sites that have recently been disturbed by some form of disturbance (e.g., a forest fire) and is common along highway roadsides. This species is only moderately shade-tolerant and does poorly in dense forests.
Autumn Olive’s resilient properties allow this species to outcompete native plants for space, sunlight, and resources, reducing biodiversity. It can also fix nitrogen, enabling it to thrive in nutrient-poor soils and displace native plant communities adapted to such conditions. The increase in soil nutrients can facilitate the invasion of other weedy species into previously unsuitable habitats. Its ability to modify soil nutrients makes this species a considerable threat to species at risk that are poor competitors adapted to poor soils, such as Rockrose (Helianthemum canadense).
Another concerning property of Autumn Olive is that it is an allelopathic plant. Allelopathy refers to a plant’s ability to produce and release biochemicals into the soil, altering the chemistry and negatively impacting nearby plants. Specifically, Autumn Olive has been shown to impact microorganisms within the soil.
Autumn Olive is native to Asia and was first brought to North America from Japan in the early 1800s. Widely sold as an ornamental plant, this shrub was also planted for various other purposes, including erosion control, roadside windbreaks, and soil reclamation. It readily escapes cultivation due to the large number of seeds it produces annually and its high germination rates. Seeds are dispersed widely via wildlife that feed on the plant’s berries.
Canada Serviceberry (Amelanchier canadensis) is a native shrub, similar in size to Autumn Olives. These shrubs produce flowers that later turn into fruit, providing food for bees and birds, which will be sure to liven up your garden!
Silver scales and small golden-brown spots on the underside of leaves with smooth, wavy edges; small red fruit with silver scales; spike-like terminal thorns.
A large, mature Autumn Olive plant can produce up to 200,000 seeds annually!
Be sure to avoid planting non-native species by using our Grow Me Instead guidebook to find excellent, native alternatives. If you spot Autumn Olive, please report it to iNaturalist or directly to the NSISC.