The first volume opens with a report on the work made by MM. Duhamel and Guettard. Then follows the Discours Préliminaire, comprising over a hundred pages, while the main body of the work opens with the Principes Élémentaires de Botanique, occupying 223 pages. The work was a general elementary botany and written in French. Before this time botanists had departed from the artificial system of Linné, though it was convenient for amateurs in naming their plants. Jussieu had proposed his system of natural families, founded on a scientific basis, but naturally more difficult for the use of beginners. To obviate the matter Lamarck conceived and proposed the dichotomic method for the easy determination of species. No new species were described, and the work, written in the vernacular, was simply a guide to the indigenous plants of France, beginning with the cryptogams and ending with the flowering plants. A second edition appeared in 1780, and a third, edited and remodelled by A. P. De Candolle, and forming six volumes, appeared in 1805–1815. This was until within a comparatively few years the standard French botany.
Soon after the publication of his Flore Française he projected two other works which gave him a still higher position among botanists. His Dictionnaire de Botanique was published in 1783–1817, forming eight volumes and five supplementary ones. The first two and part of the third volume were written by Lamarck, the remainder by other botanists, who completed it after Lamarck had abandoned botanical studies and taken up his zoölogical work. His second great undertaking was L’Illustration des Genres (1791–1800), with a supplement by Poiret (1823).
Cuvier speaks thus of these works:
“L’Illustration des Genres is a work especially fitted to enable one to acquire readily an almost complete idea of this beautiful science. The precision of the descriptions and of the definitions of Linnæus is maintained, as in the institutions of Tournefort, with figures adapted to give body to these abstractions, and to appeal both to the eye and to the mind, and not only are the flowers and fruits represented, but often the entire plant. More than two thousand genera are thus made available for study in a thousand plates in quarto, and at the same time the abridged characters of a vast number of species are given.
“The Dictionnaire contains more details of the history with careful descriptions, critical researches on their synonymy, and many interesting observations on their uses or on special points of their organizations. The matter is not all original in either of the works, far from it, but the choice of figures is skilfully made, the descriptions are drawn from the best authors, and there are a large number which relate to species and also some genera previously unknown.”
Lamarck himself says that after the publication of his Flore Française, his zeal for work increasing, and after travelling by order of the government in different parts of Europe, he undertook on a vast scale a general work on botany.
“This work comprised two distinct features. In the first (Le Dictionnaire), which made a part of the new encyclopedia, the citizen Lamarck treats of philosophical botany, also giving the complete description of all the genera and species known. An immense work from the labor it cost, and truly original in its execution.... The second treatise, entitled Illustration des Genres, presents in the order of the sexual system the figures and the details of all the genera known in botany, and with a concise exposition of the generic characters and of the species known. This work, unique of its kind, already contains six hundred plates executed by the best artists, and will comprise nine hundred. Also for more than ten years the citizen Lamarck has employed in Paris a great number of artists. Moreover, he has kept running three separate presses for different works, all relating to natural history.”
Cuvier in his Éloge also adds:
“It is astonishing that M. de Lamarck, who hitherto had been studying botany as an amateur, was able so rapidly to qualify himself to produce so extensive a work, in which the rarest plants were described. It is because, from the moment he undertook it, with all the enthusiasm of his nature, he collected them from the gardens and examined them in all the available herbaria; passing the days at the houses of the botanists he knew, but chiefly at the home of M. de Jussieu, in that home where for more than a century a scientific hospitality welcomed with equal kindness every one who was interested in the delightful study of botany. When any one reached Paris with plants he might be sure that the first one who should visit him would be M. de Lamarck; this eager interest was the means of his receiving one of the most valuable presents he could have desired. The celebrated traveller Sonnerat, having returned in 1781 for the second time from the Indies, with very rich collections of natural history, imagined that every one who cultivated this science would flock to him; it was not at Pondichéry or in the Moluccas that he had conceived an idea of the vortex which too often in this capital draws the savants as well as men of the world; no one came but M. de Lamarck, and Sonnerat, in his chagrin, gave him the magnificent collection of plants which he had brought. He profited also by that of Commerson, and by those which had been accumulated by M. de Jussieu, and which were generously opened to him.”
These works were evidently planned and carried out on a broad and comprehensive scale, with originality of treatment, and they were most useful and widely used. Lamarck’s original special botanical papers were numerous. They were mostly descriptive of new species and genera, but some were much broader in scope and were published over a period of ten years, from 1784 to 1794, and appeared in the Journal d’Histoire naturelle, which he founded, and in the Mémoires of the Academy of Sciences.
He discussed the shape or aspect of the plants characteristic of certain countries, while his last botanical effort was on the sensibility of plants (1798).