During the family summer trips, she and her brothers studied mineralogy and recorded the flow of glaciers in drawings and photographs.
After graduating from the Friends Select School in Philadelphia in 1879, she took an interest in watercolor painting. When she was not working on the family farm, she began painting illustrations of wildflowers that she saw on family trips to the Rocky Mountains of Canada. The trips to the Canadian Rockies sparked her interest in geology.
During this time she became an active mountain climber, outdoors woman, and photographer. One summer a botanist ask her to paint a rare blooming arnica and she was successful with this, which encouraged her to concentrate on botanical illustration. She spent many years exploring the rugged terrain of the Canadian Rockies to find important flowering species to paint and in 1887 on her first transcontinental trip via rail wrote an important and lengthy travel journal that was the subject of a recent article by Marjorie G. Jones in the journal Quaker History.
Over her father's fierce objections, Walcott married the paleontologist Charles Doolittle Walcott, who was the Secretary of the Smithsonian Institution, in 1914, when she was 54. She played an active part in her husband's projects, returning to the Rockies with him several times and continuing her hobby of painting the wildflowers there. In 1925, the Smithsonian published some 400 of her illustrations, accompanied by brief descriptions, in a five-volume work entitled North American Wild Flowers.
The extensive correspondence between Mary Walcott and Lou Hoover is the subject of another article by Marjorie G. Jones in the spring 2014 edition of Quaker History. From 1927 to 1932 Walcott served on the federal Board of Indian Commissioners and driven by her chauffeur, travelled extensively throughout the American West, diligently visiting reservations. Unfortunately, however, reflecting prevalent attitudes of her day, her reports are laced with criticisms of "lazy" and "ungrateful" Indians.
She was elected president of the Society of Woman Geographers in 1933. In 1935, the Smithsonian published Illustrations of North American Pitcher-Plants, which included 15 paintings by Walcott. It is awarded for scientific work on pre-Cambrian and Cambrian life and history.
Walcott died in St. Andrews, New Brunswick. A mountain, called Mount Mary Vaux, in Jasper National Park, Alberta, Canada is named after her. It is located at 52°33′0″N 117°27′10″W.
Member: Academy National Sciences. American Horticultural Society. American Association for the Advancement of Science.
Clubs: Garden of American, Colonial Dames of American, American Alpine, Canadian Alpine, Trail Riders of Canadian Rockies.