Wapato and Cous Roots


Wapato (wah-puh-toe), the Indians called it. Its scientific name is Sagittaria latifolia—from the Latin sagittaria (saj-i-tare-ee-uh) meaning "arrow-shaped" and latifolia (lat-i-fole-ee-uh) for "wide leaf." Wapato came to the Corps' attention on October 22, 1805, near the mouth of the Deschutes River.

Sagittaria latifolia Willd.

S. latifolia

Some or even all of the men may have called it arrowroot, arrowleaf, or arrowhead. If this plant was what Sacagawea was referring to when she told Clark she favored spending the winter anyplace where there was "plenty of Potas," it may be that some of the men had recognized it as "duck potato" or "Indian potato." It was first officially named and described by Carl Ludwig Willdenow (1765-1812), a physician, botanist and taxonomist who was head of the Botanical Garden in Berlin, Germany, from 1801 until his death.

In fact, Meriwether Lewis temporarily dropped behind the rest of the party "to examine a root of which the natives had been digging great quantities in the bottoms" along the Deschutes.

The leaves of this herbaceous plant are sagittate, or arrow-shaped. The leaf stems spring from the base of the plant, celery-like. Below, in the muck, are rhizomes that produce small starchy tubers at their tips, the way potatoes do.

The plant still grows, in a dozen slightly different species and varieties, in marshes, swamps, borders of lakes, streams, and ponds in every one of the lower 48 states except Nevada, as well all of Canada south of 60° North Latitude.1 Consequently it could have been recognized by all the members of the Corps of Discovery—although maybe not as food. In any case, that undoubtedly explains why Lewis didn't collect a specimen of it.

Fresh wapato might be roasted in a fire's embers, the way the expedition first tasted it on November 4, when its appearance reminded Clark of "a small Irish potato." For preservation, Native people pounded the dried roots and compressed the meal into cakes that Lewis said served well as bread. Throughout the Fort Clatsop winter, wapato was a frequent feature of the Corps' diet, obtained by trading with local people, and a welcome addition to meals of "pore elk" when they boiled meat and roots together.

The captains named today's Sauvie Island, in the Columbia River off Multnomah County, Oregon, "Wappetoe Island." On March 29, 1806, Clark recorded how the women harvested wapato—"by getting into the water, Sometimes to their necks holding by a Small canoe and with their feet loosen the wappato or bulb of the root from the bottom from the Fibers, and it imedeately rises to the top of the water, they Collect & throw them into the Canoe, those deep roots are the largest and best roots."


William Clark first mentioned the root cous2 (pronounced kows)—Lomatium cous from the Greek loma meaning "fringe" or "border," referring to the winged seed, and cous from the Chinookan informant—on November 1, 1805, saying that native people living near the future Bonneville Dam site traded beads to obtain it from people up the Columbia River. To Clark it was "cha-pel-el bread," a redundancy in Chinookan languages, because "a-s·blal" meant "bread." He was reporting its preserved appearance: for storage the roots were pounded, then roasted, and shaped into cakes. In this form, they lasted for years and were light to carry during seasonal migrations and for trading. When boiled in water, the cakes created "a thick soup or mush."3 Lewis collected a specimen at the mouth of the Walla Walla River in Washington, April 29, 1806, but whether he traded for it or gathered it himself is uncertain.

Lomatium cous

L. cous

The "biscuit root"

Cous corms


Primary Source

A. Scott Earle and James L. Reveal, Lewis and Clark's Green World: The Expedition and Its Plants, Helena, MT: Farcountry Press, 2003.

1. United States Department of Agriculture, Natural Resources Conservation Service, Plants Database, http://plants.usda.gov/core/profile?symbol=LOCO4. Accessed December 15, 2014.

2. Also called biscuit root and mountain meadow-parsley, it is a member of the carrot family.

3. Ibid., 116.
