New Voyage for Darwin’s Plants

Three million delicately preserved plant specimens – including several dating back to Darwin’s voyage on the Beagle – are being meticulously categorised and moved from their traditional holding places in the Herbarium at the Royal Botanic Gardens Edinburgh. In a radical shift RBGE has become the first botanic garden of its stature to move its herbarium collections from the 150-year-old “Bentham and Hooker” plant classification system.

The herbarium is a collection of preserved plants, which are used for scientific study and as a reference collection of named specimens. It contains many examples of species now extinct, so these remaining records are often unique.

tightening the plant press

Plants are identified in the wild, where they are collected, pressed and dried in preparation for the journey back to the Royal Botanic Garden. When they arrive they are mounted – the ones with the red (see picture below) are important as they are “types” the first of their species to be collected and “described” or named.

But what do you do with the circa 10,000 new samples which arrive each year and how do you find them when you need them? Clearly a classification system has to be in place which reflects common and up to date knowledge. In this day and age, that means moving away from the traditional Bentham-Hooker classification and recognising advancements in scientific knowledge since the advent of DNA testing in plants. The change will be to a state-of-the-art APG (Angiosperm Phylogeny Group) system, utilising new molecular data.

Herbarium with Adele SmithThe internationally acknowledged Bentham-Hooker classification system for flowering plants, which has formed the basis of the layout of the RBGE’s herbarium collection, refers to the results of a 21 year collaboration between George Bentham and Sir Joseph Hooker. Bentham spent his childhood in Russia and France. His early plant collecting in the south of France formed the basis of an herbarium of more than 100,000 specimens, which he presented to Kew. Joseph Hooker was born in Suffolk, spent his childhood in Glasgow and studied at Glasgow University, where his father was Regius Professor of Botany. Hooker devoted his career to making and describing botanical collections in North India before becoming Assistant Director of Kew. In 1865, he succeeded his father Sir William Hooker as the Director of the Royal Botanic Gardens, Kew.

“This is a massive change in the way we organise our collection and the decision to undertake such an overhaul was not undertaken lightly”, said Herbarium Curator Dr David Harris. “There is good reason why the Bentham and Hooker system has survived so long – these Victorian botanists were remarkably accurate for their time and most plant species do remain in the families recognised by them.

“Nevertheless, science continues to evolve: botanists have been trained at the Royal Botanic Garden Edinburgh for over 300 years and we aim to ensure the present generation will be taught in a place where the herbarium follows the most up-to-date reference system.”

“We now know, for example, that nutmeg is much closer to cinnamon than Bentham and Hooker had appreciated, so that will be reflected in the new layout of our herbarium. Another example is the Plane tree and the lotus flower: these two don’t look similar but we now know from DNA that they are closely related. Buddleias are no longer in the family with Strychnos – the plants from which strychnine comes – instead, they are in a family with Mulleins and Figworts. Our new system reflects such revisions in our understanding.

“Edinburgh is the first institution of this scale to embark upon the transition: only the smaller herbaria of Utrecht University, in The Netherlands, and Yale University, in the United States, have made the move to date. Because of the enormity of the task we enlisted input from colleagues at the Royal Botanic Gardens Kew, Missouri Botanical Garden and various universities around the world. It is not clear who else is going to do it next, it is not a decision to be rushed. However, we have had some very strong encouragement along the way and we aware that our move is being watched with interest”.

The RBGE Herbarium was founded in 1836 by the Botanical Society of Scotland. It was moved to its current, purpose-built, home in 1964. To initiate a seamless change to the new state-of-the-art system, the institution twice surveyed and mapped out the positioning of every one of its specimens. These will be moved to 48,000 new shelves in 4,000 protective metal cabinets in an operation of military precision. The extension, which was opened this year by Rhona Branklin MSP, will allow it to continue growing for the next 20 years.

Opening of herbarium extension

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