What is the Difference Between Autumn Olives and Russian Olives?
The terms "autumn olive" and "Russian olive" are often used interchangeably, leading to confusion. While closely related and sharing similar appearances, they are distinct species with subtle but important differences. Understanding these distinctions is crucial, especially given the invasive nature of both plants in certain regions.
The Key Difference: Botanical Classification
The core difference lies in their botanical classification. Both belong to the same genus, Elaeagnus, but are separate species:
- Russian Olive ( Elaeagnus angustifolia): This is the species more widely known for its invasive tendencies in North America.
- Autumn Olive (Elaeagnus umbellata): While also considered invasive in some areas, its spread is generally less aggressive than the Russian olive.
While their appearances overlap, careful observation reveals key differentiators.
What are the visual differences between Autumn Olives and Russian Olives?
Let's delve into the visual cues that help distinguish these two species:
1. Leaf Shape and Size:
- Russian Olive: Leaves are narrower, lance-shaped, and silvery-green on both sides, with a length ranging from 2 to 4 inches.
- Autumn Olive: Leaves are broader, ovate or elliptic, with a more pronounced, pointed tip. The upper surface is typically a darker green, while the underside is silvery. They are generally smaller than Russian olive leaves, usually measuring 1 to 3 inches in length.
2. Fruit Size and Color:
- Russian Olive: Produces larger, oblong fruits, typically ranging from 0.5 to 0.75 inches long. They mature to a silvery-grey or brownish color.
- Autumn Olive: Produces smaller, roundish fruits, about 0.3 to 0.5 inches in diameter. Their color ranges from red to orange-red when ripe.
3. Branching and Growth Habit:
- Russian Olive: Exhibits a more upright, tree-like growth habit with a tendency to form multi-stemmed shrubs or small trees.
- Autumn Olive: Often displays a more sprawling, shrub-like growth habit with dense branching.
4. Thorns:
While both species can have thorns, they are generally less prominent on autumn olives.
Are Autumn Olives and Russian Olives invasive?
Yes, both species are considered invasive in many parts of the world. However, the Russian olive's invasiveness is generally considered more significant. Its rapid growth, prolific seed production, and tolerance of various soil conditions allow it to outcompete native vegetation. Autumn olive, while still invasive, is less aggressive in its spread.
How can I identify Autumn Olives and Russian Olives in the field?
Accurate identification often requires careful examination of leaf shape, fruit size and color, and overall growth habit. Consulting a field guide specific to your region and comparing your observations with detailed photographs of both species will enhance the accuracy of your identification. Note that hybrids between these two species are also possible, further complicating identification.
What is the ecological impact of Autumn Olives and Russian Olives?
Both species can negatively impact native ecosystems by altering soil nitrogen levels, outcompeting native plants for resources, and reducing biodiversity. Their dense thickets can alter wildlife habitat and reduce the success of native plants.
In conclusion, while often confused, autumn olives and Russian olives are distinct species with subtle differences in leaf shape, fruit characteristics, and overall growth habit. Understanding these differences is crucial for effective management of these invasive plants and for protecting native ecosystems. Remember to always consult reliable field guides and resources for accurate identification.
