Charles Andreas Geyer Plant Specimens 1838 - 1839
Charles Geyer described and collected hundreds of plant specimens during 1838 and 1839 as part of the Nicollet expeditions. Although most of the 1838 specimens were lost – from Fort Snelling to St. Louis – some remain and many our housed at the National Herbarium (Smithsonian, Washington, D.C.) or the New York Botanical Garden.
Geyer, like botanists for over the past 200 years, would have “pressed” the plants in the field. Pressing a plant involves flattening it and drying it rapidly, and can be done easily by placing a plant between two sheets of newspaper and then pressing (using boards and rope) the newspaper between two pieces of cardboard. Professional collectors will also include blotting paper to speed up the rate that water is pulled from the plant.
Pressing prevents decay, and preserves color and makes it easier to mount (using glue or twine) the plant on a sheet of paper. A label is added to the sheet which provides information on where and when the plant was collected, the name of collector and features of the plant (height, abundance, neighbors, color of flowers) not visible from the mounted specimen. The pressed plant specimens are stored in special cabinets in a “herbarium,” which is literally a plant library.
Care must be taken to protect the specimen from physical or water damage and also possible depredations by insects. The Geyer sheets are often tinged with grey which at first blush appears to be mold but is actually mercuric chloride used to protect the specimens. Today, specimens are often frozen at -80°C before being added to a herbarium. The cold temperature kills insects and their eggs.