Note 225 — LETTER IX
Reading edition
The Bitterroot River rises in two forks in the main chain of the Rockies, on the northern slope of the divide between Montana and Idaho, and flows almost directly north through a beautiful, fertile valley, until at Fort Missoula it unites with the Hell Gate to form Missoula River. The name is derived from the plant Lewisia rediviva (French, racine amère), which was occasionally used by the Indians as food. The name St. Mary's River, assigned by Father de Smet, is frequently found on early maps.—Ed.