Russian Olive (Elaeagnus angustifolia)
Location: Standley Lake Regional Park, Westminster, CO, USA
The Russian Olive tree is a very common species in Colorado, especially in the eastern half of the state. These trees, with their silvery leaves, flourish near streams and at the edges of marshes. This photo was taken in September. Later in the season the fruits, which are edible, turn a golden yellow.
Native to southeastern Europe and western Asia, the Russian Olive was introduced in the United States in the nineteenth century. Originally cultivated in the U.S. as an ornamental plant, it eventually spread to the wild.
Here is a link to a fact sheet about the Russian Olive (2-page pdf) from the Plant Conservation Alliance's Alien Plant Working Group.