A herbarium is a collection of preserved plant specimens, which are used for scientific study. The majority of specimens in a herbarium are pressed, dried plants. These pressed specimens are mounted on sheets of card and stored in flat folders in banks of cupboards following a logical sequence for easy referral.
This sequence can either be arranged alphabetically, like an index, or by similarity, placing those plants that are most closely related beside each other.
Other specimens may be dried large fruiting bodies, pieces of wood or bark, seeds or material stored in spirit to preserve more delicate three-dimensional structures. A herbarium also keeps document records about the specimens - where, when and by whom they were collected.
Herbaria are used by botanists for the identification and classification of plants. They preserve most of the important features of a plant, allowing botanists to carry out research on the plants without needing to see a living specimen. As the plant is usually preserved when flowering or fruiting, the botanists can examine the most important features irrespective of the time of the year.
They also provide a historical record of what was growing in a particular place at a particular time. Many historic collections in herbaria now record plants long since lost from the locality from which they were collected. For cultivated plants, these records will give a latest date for when a particular plant was first grown.