Scientific Name
Elaeagnus angustifolia
This small- to medium-sized tree, with willow-shaped leaves and attractive stringy bark, is originally from southern Europe and central Asia and is one of the toughest tree species that grows here. It can withstand extremes of climate, drought, salt and poor soil, in part because it produces its own nitrogen fertilizer through cooperation with symbiotic root bacteria. This ability allows it to thrive in many infertile and neglected areas of the Great Plains, such as along rural highways and especially along irrigation and drainage ditches. As a result, it has been placed on the Colorado invasive plants list.
One of the best deciduous trees for creating a silvery-gray foliage effect, Russian olive produces fleshy red-orange fruit with a hard stone inside that superficially resembles an olive, though the two trees are botanically unrelated. Birds eagerly consume the sweet but dry fruit (as do people in some countries), later excreting the seeds and supercharging the tree’s invasiveness in many ecosystems.
Interestingly, Russian olive does not appear to be nearly as invasive in our urban areas as Tree of Heaven (Ailanthus) or Siberian elm. It seems unable to gain a foothold on unirrigated sites. Today, this tree is rarely planted, but it was once fairly common in suburban landscapes, and older specimens — such as the one at Claver Hall — can still be found.