Franklinia alatamaha (2003) by Herbarium Senckenbergianum Frankfurt/M.Senckenberg Nature Museum Frankfurt
A herbarium is a collection of systematically arranged dried plant specimens. Mounted on paper sheets, they are a primary source for scientific research.
What came before Herbaria?
The predecessors of herbaria were herb books which were created in the Middle Ages. These were illustrated collections of medicinal herbs with instructions on their application, kept mostly in monastery libraries. Hildegard of Bingen was a Benedictine abbess and learned scholar who lived during the twelfth century. Based on ancient monastic knowledge combined with personal experience, she developed her own medicines. Perhaps her most renowned publication was the herb book "Causae et Curae" in which she describes various diseases and the corresponding medicinal herbs.
The Invention of Herbaria
Although it did not affect botany until well into the sixteenth century, the Renaissance contributed greatly to the development of herbaria. The application and medicinal use of plants, which often dated from antiquity, became less significant and description and classification gained importance. Illustrations became increasingly detailed and naturalistic until finally scientists decided to collected and preserve real specimens.
Strictly speaking, herbaria were invented by Luca Ghini, a doctor and botanist from Italy. He taught at the University of Pisa and founded the first botanic gardens in 1544. Although he did not publish any of his own work he inspired his students to create their own herbaria. These were published between 1530 and 1545 and are considered to be the earliest known examples.
Herbar Huth (1713) by Sven Tränkner, Senckenberg Gesellschaft für NaturforschungSenckenberg Nature Museum Frankfurt
Johann Philipp Huth 1713 herbarium made up of plants from the Wetterau area (north of Frankfurt/M.)
Curating a Herbarium
Many different factors affect the preservation of plants in a herbarium. Specimens may be susceptible to mould and pests or the discolouration of petals and leaves.
Adonis vernalis (pheasant's eye) (1979) by Herbarium Senckenbergianum Frankfurt/M.Senckenberg Nature Museum Frankfurt
In order to prevent the colour of the plant from fading, the specimen should be dried as quickly as possible. The paper must be changed several times during the drying process to avoid mould.
pheasant's eye (1713) by Foto: S. Tränkner, Senckenberg Gesellschaft für NaturforschungSenckenberg Nature Museum Frankfurt
Using pesticides on the plant once it has been pressed and placed on paper will protect it from insect damage. If the insects persist, they can eliminated by placing the specimen in the freezer at a temperature of -18 °C.
Herbaria should be stored in cabinets with metal shelves away from direct sunlight. Temperature levels should be constant, between 18 °C and 22 °C with a humidity Level of 45% - 55%.
A Journey back in Time
The herbaria of the last centuries are also of significant importance for genomics. Through sequencing it is possible to reconstruct the genomes from the pressed samples. This presents a previously undiscovered picture of global biodiversity over the last 450 years and opens up an entirely new field of research. For example, by studying historical samples, information about plant diseases from the past can be used to prevent future epidemics.
Potato Blight (2017-01-01) by Senckenberg Gesellschaft für NaturforschungSenckenberg Nature Museum Frankfurt
Potato blight, which is caused by the pathogen Phytophthora infestans, is an example of an epidemic still being studied today. It caused the Great Famine in mid-nineteenth-century Ireland, resulting in the deaths of more than a million people.
Franklinia alatamaha (2003) by Herbarium Senckenbergianum Frankfurt/M.Senckenberg Nature Museum Frankfurt
Existing herbaria and documents enable scientists to understand why certain plant species (e.g. Franklinia alatamaha) have become extinct.
The Future of Herbaria
The uses of herbaria have fundamentally changed over time. Nowadays, data can be easily digitised making it more widely accessible to the public. There are numerous examples of online herbaria providing a record of regional and exotic plants. The information is presented through photographs of the object and label data.
Changing Ecosystems
The herbaria created centuries ago are of great scientific value today. Researchers use them to investigate changes in ecosystems and habitats. As date and find sites are recorded for every sample, the past distribution of a plant species can be accurately reconstructed. This gives researchers a better knowledge of previously existing vegetation and makes it possible to draw conclusions about changes in ecosystems.
[Leavenworth, Lawrence, and Galveston Railroad Bridge across the Kaw River at Lawrence, Kansas] (1867) by Alexander GardnerThe J. Paul Getty Museum
The construction of railways in the nineteenth century contributed to the distribution of various plant species (e.g. whitetop). The movement of these species can be demonstrated based on the locations and dating of herbaria specimens.
All documents and photographs, unless otherwise stated, are from: Senckenberg Gesellschaft für Naturforschung
Text and objectselection: Sophie Winterwerb (Senckenberg Gesellschaft für Naturforschung)
Collaboration: Dr. Stefan Dressler, Philipe Havlik, Sven Tränkner (Senckenberg Gesellschaft für Naturforschung)
Orto e Museo Botanico, Sistema Museale di Ateneo, Università di Pisa
Translation: Sophie Winterwerb (Senckenberg Gesellschaft für Naturforschung)
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