a lithograph of the mountain Pike's Peak

John Torrey:
Western Flora

In the 19th century, explorers, scientists, and citizens, curious about the world west of the Mississippi River, undertook ambitious expeditions into western North America. The Corps of Discovery Expedition of 1804-06—most commonly known as the expedition undertaken by Captain Meriwether Lewis (1774-1809) and Second Lieutenant William Clark (1770-1838)—is among the most famous exploratory missions. This expedition, and the many others that followed, involved collection of hundreds of plant specimens. By the 1840s the concept of Manifest Destiny—the idea that the nation should extend from the East coast to the West coast—led to the establishment of the Corps of Topographical Engineers, a new branch of the army. Members of this group surveyed and mapped their way across the continent, the first step to the establishment of transportation routes.

Civilian scientists were regularly employed on these missions, describing and documenting the plants and minerals they encountered. John Torrey, often in collaboration with Asa Gray, studied the plant specimens collected by many of these intrepid travelers. Specimens from nearly every federally-sponsored expedition to the west and south during the 1800s were referred to Torrey for classification. As these new discoveries came to light, American botanical knowledge grew.

Image: Pikes Peak. In Report of the Exploring Expedition to the Rocky Mountains in the year 1842, and to Oregon and North California in the years 1843-44. Washington: Gales and Seaton, printers, 1845. LuEsther T. Mertz Library, The New York Botanical Garden.