by Kathy Lloyd, Montana Native Plant Society
American silverberry, also called wolf-willow, was collected by Captain Meriwether Lewis on July 6, 1806. It was a busy day for botany and Lewis collected a number of other plant specimens on the same day. Lewis and his party of men were in the Ovando Valley in what Lewis called the "prairi of the knobs," and were traversing the Blackfoot River in preparation for crossing present-day Lewis & Clark Pass. They wanted to explore the Marias River to its headwaters, and so had separated from Captain Clark and the rest of the explorers, who were on their way back to Camp Fortunate in Beaverhead County.
American silverberry goes by the scientific name Elaeagnus commutata and is a member of the oleaster family (Elaeagnaceae). The original specimen collected by Lewis can be seen today at the Academy of Natural Sciences in Philadelphia. The specimen sheet includes a hand-written note by botanist Frederick Pursh that says, "Silver tree of the Missouri From the prairi of the Knobs. Jul. 6th 1806." Wayne Phillips, author of Plants of the Lewis & Clark Expedition, believes the note indicates Lewis told Pursh he had seen American silverberry on both sides of the Continental Divide, both east along the Missouri River, and west where he collected it in the Ovando Valley.
American silverberry is a deciduous, long-lived perennial shrub that grows from three to 13 feet tall. It is erect, strongly rhizomatous, and often forms thickets of flexible willow-like branches. The leaves are alternate, silvery and about two inches long. The flowers are tubular and sweet-scented with a lemon-like fragrance.
American silverberry can be found from Alaska and the Yukon Territory, east to Quebec, and south from British Columbia and Quebec to Minnesota, Colorado, and Utah. It is also found in Texas and Kentucky and is rare in South Dakota. It is an important component of the native mixed-grass prairie of the northern United States and southern Canada and in Montana is commonly found with rough fescue, Idaho fescue and bluebunch wheatgrass. American silverberry can thrive on sites in warm, open, sunny grasslands, as well as those in cooler, forested areas and woodland thickets. Where Lewis found the shrub in southwestern Montana, it occurs in moist areas along streams and near springs and seeps. American silverberry grows best in loamy soils, but is also commonly found in dry, sandy or gravelly soils on exposed hillsides.
Wildlife, particularly moose, relies on American silverberry for food. It's possible that Lewis observed moose browsing on American silverberry as he journeyed along various river systems in Montana. Elk also eat the shrub, and small mammals, birds and waterfowl use it for shelter.
The Blackfoot Indians and other tribes made use of American silverberry for food and medicine. A decoction of bark was mixed with grease and applied as a salve for frostbite. The fruit was also eaten, mostly peeled and added to soups or mixed with grease and eaten as candy. The Blackfoot also made a strong rope from the bark and soap from the berries. Necklaces were made from the cleaned seeds. Later in July, Lewis and his group would have an encounter with the Blackfoot Indians that sent them hustling back to the Missouri River.
Today, American silverberry is used for rehabilitation projects and in native landscaping. It is adapted to erosive soils where its rhizomes, underground stems, help hold the soil in place. The shrub spreads mainly by rhizomes and can increase quickly. It also reproduces by seed. It can tolerate moderately alkaline soils and has been used to revegetate mine sites. The species is somewhat drought-resistant and can be used in native, low-water plantings. The plant fixes nitrogen, which may be available to other plants growing nearby.
American silverberry sprouts from its rhizomes after fire, and probably establishes from seed as well. But it does not recover quickly after fire.
American silverberry is listed as a sensitive species in Idaho. As with all native habitats, care should be taken not to disturb the native plant associations found with American silverberry and to avoid the introduction of exotic species.