Tuesday, 5 August 2014

Silent witnesses of the ages

William Dampier, a collector, known as a pirate too
One of my Biology tasks at a secondary school was to go out into the wild, collect certain plants, dry them and mount them on nice sheets of paper. I made my first herbarium and I was surprised how much I enjoyed it. But it was not just fun. By walking in the woods with an atlas of plants in my hands I learnt how to identify flowers and trees and I learnt a lot of scientific names. It was a great empirical learning experience. But I did not think much about where all this information in the book came from. I did not realise that someone in the past had to find the very same plant, describe it, name it and put it in the system. I would hardly connect all the scientific descriptions with pirates or adventurous trips to remote places of the world in the past. 

However, now I know that a great number of scientific names and features of various plants are globally known thanks to collectors and travellers. They brought the plants they had found on their voyages back home and after a precise description and identification they stored the plant collections for future generations. Today, we can literally touch these beginnings of systematic science at various Herbaria in the world. Oxford University Herbaria store the oldest collections in the UK and the OBGHA is proudly collaborating on updating the collections with new specimens collected and mounted at the Botanic Garden.

HERBARIUM – a treasure behind the word

The Herbarium of
Jacob Bobart the Elder

A herbarium, as a permanent record of plant species, is a collection of dried preserved specimens. The term also refers to a building, a scientific institute where the specimens are stored and researched. Oxford University Herbaria, established in 1621, includes the oldest Herbarium in the UK and is the fourth oldest in the world. It is home to approximately 1,000,000 botanical specimens, rare botanical books, manuscripts and illustrations. The total collection comprises phanerogams, angiosperms, gymnosperms, algae, lichens, fungi, ferns, slime moulds, liverworts, mosses, hornworts. Moreover, incredible collections of fruits, seeds, pollen, wood and spirit-preserved material can be found in the Herbaria collections.

A sheet of marine plants produced as a souvenir

Lichens collection
Fungi collection

Amongst all the treasures, the Herbaria shelter 30,000 type specimens, which are of significant importance.  A type specimen is a specimen, which was first used by researchers when new species were described and to which the scientific name was formally attached. There are also some historically important collections such as the herbaria amassed by William Sherard, Charles Du Bois, William Dampier or John Sibthorp. Moreover, a great prominence is given to the collections of plants which are now extinct in the wild.

Is the physical material so important?

We already know that the herbarium is a collection of dried plants that has been brought and collected together from across the world. But why is it so important to collect plants, dry and store them for other generations? Well, there are a couple of reasons that have encouraged the collectors and botanists to gather plants for centuries. As Dr Stephen Harris, the curator of Oxford University Herbaria, explained: “Plant collections allow us to identify and locate plants in time and space, to answer fundamental questions about plant evolution and reveal the diversity of plant life.” 

Furthermore, herbaria are essential for:
  • the study of plant taxonomy
  • the study of geographic distributions
  • the stabilising of nomenclature
  • gathering information about population, climate, and scientific and historical changes

Researchers from many disciplines find the collections very useful.  For instance, they use the collections as sources of DNA for phylogenetic analysis, of pollen for climate change analysis and of stems for carbon dating.

The process of creation

The plants collected in a field or in gardens (in our case at the University of Oxford Botanic Garden and Harcourt Arboretum) are spread flat on sheets of newsprint and dried in a plant press, usually between cardboard sheets. When dried, the specimens are mounted onto sheets of acid-free paper by using a special acid-free paper tape, acid-free linen thread or pH-neutral glue. Soft or bulky parts of plants, as well as fruits and seeds are put into paper or display envelopes. As paper was expensive in the past, multiple specimens were mounted on one sheet and bound into a book (e.g. the Herbarium of Jacob Bobart the Elder). The modern preference is to mount one specimen per sheet. The sheets are then sealed into plastic bags, frozen and then acclimatised back to room temperature. An important part of such a sheet is a label with all the important information about the plant: the name and the family of the specimen, locality, description of the plant, accession number, date of collection and who has collected it. All this information comes from the database connected to BRAHMS, into which it was typed soon after collection.

Malus 'Ormiston Roy'
(mounted specimen)

Malus 'Ormiston Roy'
(living plant)

Magnolia sieboldii ssp. sinensis

Magnolia sieboldii ssp. sinensis

Nearly four centuries of botany lie on the sheets of herbaria. The dried samples have witnessed the progress of botany from the early steps of first collectors, who tried to transform the unknown wild plants into precisely described and named scientific specimens, towards the molecular approaches of modern scientists. It is a great pleasure to continually update these collections and become a part of that history... the history of beautiful botanical collections with great historical value and significant contribution to science.

Veronika Zvijakova
(Erasmus student at the Botanic Garden)

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