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Lewis's Mockorange

Photo of Lewis's Mockorange.

Lewis's Mockorange

Philadelphus lewisii

by Kathy Lloyd, Montana Native Plant Society

It's no wonder that Meriwether Lewis collected specimens of Lewis's mockorange, or syringa as it is also known. This beautiful, deciduous shrub, with sweet-smelling white flowers, would have caught the attention of the expedition's naturalist. Indeed, there are two specimens of Lewis's mockorange mounted on a single specimen sheet in the Lewis & Clark Herbarium in Philadelphia today. The first specimen was collected on May 6, 1806 along the Clearwater River in Idaho. The annotation made by the botanist Frederick Pursh, who was commissioned to look at the expedition's plant specimens, says, " A Shrub from the Kooskoosky. May 6th 1806. An Philadelphus?" The second specimen was collected in Montana along the Clark Fork River between Grant Creek and the Blackfoot River. This collection was made on July 4, 1806. Lewis and his party of men were on their way to the Marias River drainage, while Clark and his party headed south. The label applied by Frederick Pursh to the Montana specimen says, "On the waters of Clarks R Jul. 4th 1806."

Lewis's mockorange was new to western science and Pursh named the plant in honor of Meriwether Lewis, calling it Philadelphus lewisii. The genus Philadelphus has recently been placed in the Philadelphaceae family, but it traditionally has been considered a member of the hydrangea (Hydrangeaceae) family. Today, Lewis's mockorange is the state flower of Idaho.

Lewis's mockorange can be found in the northwestern United States and southern Canada, from southern British Columbia and southwestern Alberta (where it is rare) south to California, Idaho, and western Montana. Lewis and Clark probably noticed it as they traveled through Montana and Idaho in 1805, but both collections were made on the return trip in 1806.

This attractive shrub commonly occurs in open coniferous forests, on the edges of forests, and on slopes with other shrubs such as common chokecherry (Prunus virginiana) and serviceberry (Amelanchier alnifolia). It often occurs with the shrub ninebark (Physocarpus malvaceus) on talus slopes in western Montana. It thrives in well-drained, moist draws and riparian areas, where Lewis collected it, and does best with a northern or eastern exposure.

Lewis's mockorange can grow from three to 10 feet tall and has stiff, erect stems. The showy, white flowers have the scent of orange blossoms and occur in clusters of three to 15 on the lateral branches. Each flower has four petals, four styles and numerous stamens. The leaves are opposite and simple. The shrub can reproduce both vegetatively and by seed, and can sprout from the root crown following fire or other disturbance. Flowering of Lewis's mockorange occurs from May through July. The specimen that Lewis collected in May in Idaho was in flower, while the one from July in Montana was not.

Lewis's mockorange provides some winter forage for deer, both white-tailed and mule, and elk in the northern Rocky Mountains, but the percentage is fairly small. At times, however, it is heavily browsed. Since Lewis's mockorange is generally not a preferred browse species, range managers can use it to determine the quality and quantity of browse species and gauge the extent of the deer population. The new sprouts are very palatable and are consumed by deer and elk. Quail and squirrels eat Lewis's mockorange seeds and the dense shrub habitat common with Lewis's mockorange provides good cover for wildlife.

Native Americans in the Rocky Mountains and Pacific Northwest used Lewis's mockorange to fill numerous needs. Various salves and compresses were used externally to relieve swellings, as an antirheumatic, for sores, hemorrhoids and eczema. A decoction was taken internally for lung problems and as a cathartic. The strong, hard branches of Lewis's mockorange were used for bows, arrows, digging sticks, fish spears, and clubs. Brooms, combs, tobacco pipes, cradle hoops, and snow shoes were also constructed using material from Lewis's mockorange. Today, Lewis's mockorange is cultivated as an ornamental and makes a lovely addition to a native plant garden or any other landscape setting. Lewis's mockorange is one of our special plants, both because of the history attached to the species and because of the niche it fills in our native bionetwork. Plan a trip to the woods in May or June and take time to smell Lewis's mockorange and think about the years it has been a part of our Montana landscape and the first white men to smell its wonderful fragrance.