Pressing Plants

The Linnean Society of London is home to an extensive herbarium, which is a collection of plant specimens preserved for the purposes of identification, research and education. These collections are crucial for ongoing research on plant biodiversity.

In order for a herbarium specimen to be of use to a researcher, it needs to be displayed in such a way that all of the plant’s key structural parts can be seen and studied.

How to press plants:

1. In dry weather, collect a whole plant, including the root system; one which is healthy, has average-sized leaves and flowers, and which is no bigger than an A4 sheet of paper.
2. Record the following: the date the plant was collected, the location it was found, the dimensions of the plant, and its colour, using a colour chart, like the one made by James Sowerby (lower image).
3. Remove any excess soil attached to the specimen and place it on top of blotting paper that has been laid on top of a solid flat surface. In the following order, place on top of the plant another piece of blotting paper, one sheet of stiff card (corrugated or other), and then a heavy object such as a book or brick.
4. Ensure that pressing occurs in a warm, dry and well ventilated room. Check on the plant every 24 hours. The drying process can take from 3 days up to 3 weeks depending on the specimen.
5. Once dry, attach the plant to an A4 sheet of paper by sparingly using PVA glue and tape. Write the information recorded when the specimen was collected onto the paper on which the plant has been mounted. Finally, title the herbarium specimen with its species name.