French botanist. Michel Adanson was the son of the equerry to the Archbishop of Aix-en Provence. His family moved to Paris in 1730 when his father's employer assumed responsibility for the archdiocese. He was destined from an early age for the priesthood and, through his connections to the Church, was provided with a canonry from Champeaux en Brie, which paid the cost of his education. At college, however, he demonstrated an extraordinary aptitude and passion for the natural sciences and afterwards went on to study and work under the direction of Réaumur and Bernard de Jussieu.

While he was cataloguing the plants that had been grown in the Jardin du Roi since 1740, Adanson began to play with the idea of a classification system capable of describing all living plants. He was determined to travel to some little-known region where he could discover new plants, and used his connections to secure a position at the trading post in St Louis, Senegal. Before leaving, he gave up his stipend, forfeiting his ecclesiastical career, and acquired the various skills he would need to collect data on the country's flora and fauna, resources, population, and geography. For five years (December 1748 to February 1754) he charted maps, collected artefacts, made astronomical and meteorological observations, and wrote grammars and dictionaries of some of the languages. Mostly, however, he collected specimens. He brought back to Paris some 30,000 plant specimens and a large collection of molluscs and fish. In addition to studying the natural history of St Louis and its surroundings, he made several journeys to the interior, including trips to Gorée Island, Podor, and the Gambia River. He collected on Tenerife on the voyage out, and on Fayal, on the voyage back. While still living in Senegal, he sent shipments of several hundred plants to Bernard de Jussieu, which were worked on by A.L. de Jussieu, for his Genera Plantarum, and by many later botanists. He presented Linnaeus with a number of plants from his collection before the break in relations over their competing systems of classification.

Only the first volume of his planned Histoire Naturelle du Sénégale (Paris, 1757) was ever published. It contains an account of his travels, followed by a description of shells, but few mentions of plants, because he was reserving his botanical discoveries for future volumes. Although the publication represented only a fraction of the work for which he collected notes, it made his reputation and led to his election into the French Academy of Sciences and the Royal Society of London. In spite of his celebrity he lived a solitary existence, without students and almost without friends; and apart from some rare trips to the sea or mountains, and occasional presentations to the Academy (such as the first description of a baobab tree, in 1761), he confined himself to his study, busily analysing, determining, and classifying the thousands of specimens of plants, fish, and molluscs he had brought back from Senegal, and preoccupied with his idea for a universal method of classification.

For his descriptions of Senegalese molluscs he applied an entirely new method of classification that was based on the anatomy of the living animals inside the shells rather than on the shells alone. Many of his genera are still in use today. In 1759, while working with the Jussieus on a manuscript plan for the gardens at Versailles, he completed his outline for the plant classification system that he had originally conceived as a student in the Jardin du Roi. Familles Naturelles des Plantes, published in 1763, owed much to the classification of plant families developed by Bernard de Jussieu for the flower beds at the Grand Trianon, and was inspired by the system of Joseph du Pitton de Tournefort and by the empirical approach of John Ray. Adanson rejected previous classifications for their reliance on a few arbitrarily selected characters that do not apply to all plants; instead he proposed a system based on all characters, or rather 66 categories of characters, which when combined and united would permit the classification of all living plants, known and as yet unknown to science, without exception. Satisfied with the correctness of his method for botany, he resolved to apply it to the other branches of natural history, and ultimately to all human knowledge, to create, in his words, a universal method (la méthode universelle). Although his Familles Naturelles des Plantes was appreciated within the scientific community for its observations and discussions of family relationships, the classification system it introduced met with no success and was harshly criticised by the supporters of Linnaeus. Adanson was undaunted. Having contributed several hundred articles on botanical subjects to Panckoucke's supplement to the Encyclopédie (which were later incorporated by Lamarque into his Dictionnaire de Botanique), Adanson began work on an encyclopaedia of natural history based on his universal method. In 1775 he convened the Academy to present his outline of L'Ordre universel de la nature. The committee of inspection baulked at the piles of material: 27 manuscript volumes explaining the relations and distribution of all known beings and substances; 150 manuscript volumes listing 40,000 species in alphabetical order; a vocabulary of 200,000 words; 40,000 illustrations; 24,168 specimens; plus scores of memoirs and observations. The committee, in their rejection of the proposal, advised him to separate his own work from what was merely compilation. Adanson, however, remained convinced of the superiority of his project and spent the rest of his life in futile attempts to have his encyclopaedia published, revising and developing its various parts, expanding the supporting herbarium and illustrations.

Then came the French Revolution which ruined Adanson financially, but not politically. With the dissolution of the Academy he lost the pension that had been granted to him when his natural history collection was absorbed into the Cabinet du Roi, but he did not allow his poverty to interrupt his work. When the newly reconstituted French Institute invited him to take his place amongst his old colleagues, he sent the reply that he had no shoes in which to appear before them, although visitors to his cabinet knew that he always found the money for fresh supplies of paper and ink. At length the French Institute renewed his pension and Napoleon made him a member of the Légion d'honneur . Quoted more than a hundred times in Buffon's Histoire Naturelle, Adanson died convinced that posterity would recognise the superiority of his system. The baobab genus Adansonia L. is named after him.

Sources:
C.C. Gillespie (ed), 1970, Dictionary of Scientific Biography, 1: 58-59
J. Vallot, 1883, Études sur la Flore du Sénégal: 11-12
M. Prevost and J. Balteau, 1933, Dictionnaire de biographie française, 1: 506-7.