Pressed Plants and Flattened Flowers

herbarium group

Hull Museums include several small herbaria collected by Robert Mortimer, Cecil Wright Mason and Eva Crackles. The collections contain specimens from North and East Yorkshire and include grasses, ferns, flowering plants and seaweeds.

What is a Herbarium?

A herbarium is a collection of dried plants and flowers mounted on paper, and stored, catalogued and arranged systematically for study. The word 'herbarium' was originally used to refer to a book about medicinal plants but its use widened to describe a general collection of dried plants.

In the early 16th Century, Luca Ghini, a Professor of Botany at the University of Bologna, Italy, is thought to have been the first person to dry plants under pressure and mount them on paper to serve as a lasting record. This practice spread throughout Europe and by the 18th Century it was well established.

There are four main types of herbaria; international, national, local and historical. These usually reflect the size of the collections and the areas or region from which they were collected.

Collecting Plants

Hop Trefoil, Rough Chervil, Sulphur Clover

Plant collections usually originate from expeditions undertaken by botanists (somebody who studies plants) or through an exchange with another collector. The specimens in a herbarium form a working reference collection used to identify plants and to study the relationships between different plant species.

Each sample in a herbaria records information about where it was found, when it flowers and what it looks like. This information is enough for scientists to study the evolution of that species and can also help with conservation and ecology studies.

Medical Uses

Herbariums also have a medical use with a long association between plants and medical treatments. One of the most effective painkillers today is morphine extracted from the plant Papaver somniferum (opium poppy). Herbaria have provided knowledge of the benefits and dangers of using the opium poppy and to note which part of the plant should be used and the season it should be harvested.

Preserving and Storing Specimens

The most common technique used to preserve a collection involves pressing and then drying the plants. Specimens are usually pressed, between sheets of blotting paper to absorb the moisture, and then dried under a low heat. This is usually done as soon as possible after the plant was collected to preserve its original shape and colour; essential for the accuracy and reference value of the collection. A final process, that has been introduced recently, is to place the specimens in a freezer for several days in order to kill any insects that may still be on the plants.

Once the specimen has been preserved and identified they are then mounted on hard paper or card, known as herbarium sheets. Specimens are either strapped down with 'paper tapes', glued or stitched to the sheet. These sheets are then typically organised systematically, by family, genus and species. Delicate plant parts, such as flowers, fruits or seeds, not suitable for pressing can be preserved in spirit. These specimens are stored in jars of alcohol, used to prevent them from becoming brittle.

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