Tuesday 29 October 2013

Ernest-Henry Tourlet and his Herbarium

In the Middle Ages herbariums (herbiers) were collections of illustrations of plants, not dried plants. It was Lucas Ghini, a 16th century Italian physician and doctor to the Pope, who had the idea to dry actual plants for reference. The 18th century French scientist Larmarck said that you became a botanist by picking plants, studying them and creating a herbarium.

In these early days, botanists were principally pharmacists, and the 19th century Ernest-Henry Tourlet (1843 - 1907) was no exception. He was an amateur botanist, and by profession a Pharmacist 1st Class. In those days there was two levels of qualification for many professions, and his father had been a Pharmacist 2nd Class. There was also two levels of high school baccalaureate, and so Tourlet, who began school in Chinon, his home town, had to finish at the prestigious Lycée Impérial (now Lycée Descartes) in Tours. He became interested in botany first through the influence of his father, and then with the encouragement of Alexandre Boreau, the Director of the Botanic Gardens in Angers. Although none of Tourlet's own pharmacy students took up botany, one of his sons became a doctor (the other was a career soldier killed in combat).

After finishing school Tourlet chose to go to Paris to study pharmacy. (The only other place he could have gone was Strasbourg.) He took on some extra subjects at the Sorbonne, studying natural science and chemistry. He wrote his thesis comparing the lives of plants and animals. On graduation his first job was at the Hôtel-Dieu, the oldest hospital in Paris.

Although encouraged to stay, he didn't like living in Paris and decided to return to Chinon. At this time, Chinon had a population of 6000 and was un petit trou perdu ('a hole in the middle of nowhere'). In time he purchased a substantial residence in Chinon, and a farm house at Champigny sur Veude. His collection grew so large and he accumulated so much material that he needed all the available attic and cellar space in both properties. (Both houses still exist, but the areas around them have changed greatly.)

 The local botany club on the Puy Besnard just outside of Chinon, a site of high botanical interest that Tourlet must have known well.
He was an inveterate botanist and collector, even collecting on his honeymoon in Arcachon. His wife knew what she was in for from the start, and it was she who gifted the herbarium to the School of Medicine and Pharmacy at François Rabelais University in Tours after her husband died.

He created the most important herbarium in Indre et Loire, containing 11 000 sheets of specimens covering 1530 species, collected in almost every commune of the department. He also made a general herbarium, with plants from the whole of France, Europe and the French colonies, especially North Africa. The plant specimens were acquired by swapping, buying and collecting in the field. There is also a smaller moss collection which he created with two friends (together they were known as les trois Ernests). One of the members of the botanical society I belong to (the Association de Botanique et de Mycologie de Sainte Maure de Touraine) has recently reviewed all the identifications in this last herbier.

 A typical view of the countryside around Chinon.
A botanist's activities in Tourlet's time primarily consisted of collecting specimens, either alone or in groups, identifying the plants collected, and putting them in a herbarium. To this end he carried a press, paper and pencils almost everywhere. Mostly he walked, often great distances. Later he might take a horse drawn bus in order to be able to range farther afield. When he became a bit wealthier he hired a Victoria (a four wheeled horse drawn vehicle) and after 1880 he travelled by train.

He collected some species many times. For example, there are 37 specimens of Pasqueflower Pulsatilla vulgaris in the collection. All his collecting trips are recorded in his cahiers d'herborisation (field notebooks). A network of other amateur botanists supported him, such as Aristobile in Preuilly, Sennegon in Chaumussay and Audebert, the head gardener at the Chateau of Candé. He would request that they collected certain species and their specimens would be dispatched by train to him.

 The bridge over the Vienne at Chinon (during the 2011 works to strengthen the Medieval foundations).
Specimen plants were pressed and dried, then fixed to sheets of paper impregnated with the poison bichlorate of mercury to ensure they were protected against insects and mould. (Background levels of mercury in paper are about 0.3 mg/g, whereas Tourlet's herbier sheets contain 0.5 - 5 mg/g.) Each sheet of specimens was labelled with the name of the species, the place found and the date. The conservators working on the restoration of the herbarium had to have their urine tested once a week to ensure their levels of mercury were not going up.

Determinations (identifications) were made using the work by DuJardin, the only good Flora that existed for the area. Tourlet also corresponded with all the prominent botantists of the time, such as Gustave Rouy and the Abbé Coste, as well as writing scientific articles himself. The arguments were starting between the lumpers and the splitters, so there was a lot of correspondence flying about! I love the French expression for those taxonomists who habitually split established species into many new species with finely nuanced differences -- they pulverisé les especes!

Tourlet's penultimate project was to create an inventory of vascular plants in Indre et Loire (in fact, finished after his death by Jean Ivolas). It lists each commune a species was found, who collected it, any subspecies, and the type of habitat it preferred. Today it is responsible for certain plants believed to be locally extinct being refound. Finally, there is his Flora, still only in manuscript form, but with a dichotomous key for identifying the plants of the area.

The herbarium is both a set of historical documents which must be preserved and a modern scientific study tool. It tells us much about the way of life of a 19th century botanist as it also includes more than just plant specimens -- scientific journals/articles, tickets and delivery notes, correspondence. There are so many documents we can follow Tourlet's life on an almost day to day basis. Like many of his generation he corresponded most days (including to fellow botanists on the eve of his wedding). The documents can be used to verify and cross reference the sometimes barely decipherable specimen labels. It is the only complete herbarium for Indre et Loire, and is an important tool for monitoring biodiversity today.

The work is so thorough it can tell us not just about changes in wild plants but cultivated ones too. For instance, in 1802 there were 180 sericultures (farms growing silk worms) in the Chinon area. Tourlet tells us that by 1866, due to a severe outbreak of disease, there were only 70 remaining. We also know from Tourlet that by 1815 licquorice was no longer grown in the area, out competed by cheaper imports. Other aspects of history are touched on too. He records Hoary Alyssum Berteroa incana for the first time in 1870. It is not a native plant, but a weed which arrived as seeds in the hay brought to feed the Prussian horses when their troops invaded.

Tourlet's herbarium holds the type species (echantillons types) for a number of French native plants. These are the benchmarks against which all other identifications of the species are compared and the specimen on which the original taxonomic description of the plant was based. The specimens can be used for DNA testing as they are already existing well identified plants with many samples immediately available. This is a surprisingly rare commodity.

For all of these reasons the Ministry for Research provided a grant to conserve the collection and get it into a state where it could be used as a scientific resource once again. One of the main aims of the project was to put the collection online. When the University Pharmacy Laboratory team lead by Marc Rideau started, they had a working botanist's herbarium, not a proper archival collection. Specimens weren't fastened to their sheets, labels had faded.

The first step was to re-present all the specimens, giving them new acid free museum quality paper (Heritage Woodfree) sheet backings, fixing them down with reversable glue (Evacom) and removing all metal fixings. The original sheets are quite well preserved, but without transferring the specimens to acid free (and mercury free) paper, they are impossible to use. Also the quality of the original paper Tourlet used fluctuated, probably with his changing financial circumstances and with changing manufacturing processes in his lifetime.

Next the identifications had to be checked and new labels written (the old ones were frequently a challenge to decipher). The sheets were grouped taxonomically and put into sleeves. An image bank was created, including all the old labels. Now there is an online searchable database of the whole herbarium and the university has applied to Monuments Historiques for formal listed status for the herbarium, to give it legal protection for the future. This requires the creation of a new category of object which can be listed by Monuments Historiques.

It has been a pioneering and benchmark project. The University now wants to assist with doing the same for every historic herbarium in France in museums and universities.

Source: This post is written from the notes I took at a lecture given by Marc Rideau, Emeritus Professor, University of Tours. Apologies to Marc if I have misunderstood or got anything wrong.
Fungi Foray: The Association de Botanique et de Mycologie de Sainte-Maure-de-Touraine will be holding a fungi foray in the Forest of Loches on Saturday 2 November. Meet at 2 pm at the Pyramide de Saint-Quentin (on the D31, Bléré road, between Saint-Quentin and Loches). The fungi gathered will be laid out and identified by experts at the end of the outing. The emphasis is on learning to identify all types of fungi, but there is nothing to preclude you attending and collecting edible species for personal use.


Tim said...

"licquorice was no longer grown in the area"...
Liquorice returns... I've recently been sourcing seed... it is quicker and easier from straps, but I just cannot find a source in Europe.

Found three suppliers, all in the UK, but to make it economical, I need Pauline to say what other seeds we want and then work up a list.

This is a superb post Susan...
with the result that I am now 25 minutes behind on today's tasks...

Susan said...

Tim: Thank you, glad you found it interesting.

chm said...

Thank you Susan for this fascinating post. Glad Monuments historiques got involved. Since laws about French heritage (patrimoine) were passed, it seems the label Monument historique involves more than just buildings. I was very surprised one of my grandfather's paintings got that label a few years ago.

RestlessinFrance said...

Extremely interesting and how intelligent to listen to a lecture in French and write notes. Truly amazing.

Susan said...

Sweetpea: The speaker was excellent, with a good delivery style and powerpoint. I already knew something about the subject. My notes are a big jumble of franglais. It's good practice for my French comprehension, but I would only do it for something I was interested in and therefore already know something about. It makes a big difference if you know roughly where the lecture is going to go and you can hear the speaker clearly.

the fly in the web said...

That was fascinating...especially the changes over the years.
That's a proper use of public money, to make it available to all.

I heartily agree about it being easier to pick up something in a foreign language if you know the context...

A friend's mother used to live in that house on the side of the bridge and he said she told him that when it was being bombarded when the Germans were retreating her friends asked her why she didn't move out.
No fear, she is reported to have said, the bridge won't be hit...it's the Americans bombing it...

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