Specimens come to the Harvard University Herbaria from across the world. Shipments may arrive from as far as Australia, China, Russia, or as close as areas in neighboring Massachusetts towns. They arrive in boxes dotted with bird droppings, the specimens within wrapped in newspaper or stored temporarily within commercial containers and bags. The packaging from the field is sometimes nearly as interesting as the specimens themselves, as some come in exotic bags and wrappings.
Temperature and humidity control in herbaria are vital to the survival of the specimens. High temperature and high humidity will invite mold to germinate, insects to swarm and thrive, and specimens to age more quickly. Low humidity will dry paper and specimens, making them brittle. Fluctuations in temperature and humidity cause further damage to the specimens. The comfort level for humans and that of botanical specimens differ, and finding a reasonable compromise is difficult. Low temperatures are better for specimens, yet when curators work in the same environment, the environment must meet their needs as well.
The most common insects in the Harvard University Herbaria are silverfish, cockroaches, and beetles, primarily the Herbarium Beetle. Curator Genevieve Lewis-Gentry says that she often sees silverfish scuttling over her keyboard and swarming in spaces within the herbaria. Cockroaches, most commonly the American, German and Oriental, can be seen creeping along the shadows and edges of walls in the basement. Beetle damage is recognized by the small holes they leave as they eat through paper and specimens. Beetle larvae cause much damage as they eat their way to adulthood, crawling and munching through materials. When freezing specimens, temperatures must be low enough to kill not only the adult insects, but also their eggs. Low temperatures, low humidity, and a clean, secure building are the best prevention for insects.
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The cabinets in which the specimens are housed have changed over the years. Older cabinets, made of wood or metal, were not airtight and allowed insects to enter, as well as light, temperature, and humidity to damage the specimens. More modern cabinets are airtight and better protect specimens against harmful particles in the air, as well as fluctuating temperature and humidity.
Labels are nearly as important as the specimen itself. A label tells where the specimen has come from, who collected it, the plant's features and habitat, the date, the scientific and vernacular name of the plant with variations over the years, and other supplementary information. We know today that the paper used in making labels should be acid-free to prevent degradation over the years, but in the past labels were made without this in mind. Many of the labels in herbaria are becoming brittle; their glued backings are crumbling, their text is fading, the paper is becoming discolored and cracking... too many are coming loose from the specimen and becoming lost amongst the shelves. With the loss of these labels often the identity and provenance of a specimen is gone. Without their identifiers, they are simply objects with no names.
Other dangers lurk sometimes unrealized by curators. This specimen, which had been housed in the Harvard University Herbarium wood anatomy lab, has an unknown chemical reaction growing upon it which resembles mold.
For all the care and devotion of their curators, botanical specimens have inherent flaws that play against them. They are susceptible to heat, cold, humidity, mold and insects, as well as to chemicals once thought to protect them. Despite our efforts to prolong their lives, our methods cannot always have a happy ending. And yet, to step away from science and to observe these specimens from a different perspective, the flaws can be touchingly beautiful. The narrow winding holes made by beetles, the fading and distortion of color, the mystery when identity and provenance are swept away by time and dust can capture the mind of an explorer and create intrigue in the hidden dark corners of herbaria. We cannot suspend forever the lives of specimens, but we can respect and appreciate the delicate fragility of science.
Bridson, Diane. The herbarium handbook. Royal Botanic Gardens, Kew, 1998.
Conservation Online. Environmental Monitoring and Control, Stanford University. Click here for Conservation Online
Copeland, Marion. Cockroach. London: Reaktion, 2003.
Patkus, Beth Lindblom. "Integrated Pest Management." Preservation Leaflets. North Andover, Mass.: Northeast Document Conservation Center, 2007. Click here for NEDCC Leaflet