WILLDENOW, KARL LUDWIG

(b Berlin, Germany, 22 August 1765: d Berlin 10 July 1812)

botany, historical phytogeography.

As a botanist in the Linnaean tradition, Willdenow was concerned chiefly with description and classification although he also helped lay the foundations for the new field of phytogeography that emerged in the early nineteenth century. He was introduced to the study of plants by his father, Karl Johann Willdenow, a Berlin apothecary, and by the botanist Johann Gottlieb Gleditsch, He also was taught chemistry by his father’s friend and colleague Martin Heinrich Klaproth. After receiving his early formal education at a Berlin Gymnasium. Willdenow studied at the pharmacy school conducted by Johann Christian Wiegleb at Langensalza. He completed the course in 1785 and then went on to study medicine at Halle, receiving the M. D. in 1789. In 1790 he married Henriette Louise Habermass and took over his father’s establishment in Berlin.

By this time Willdenow had already published a flora of Berlin (1787), and for several years he had been conducting informal botanical lessons and field trips in and around the city. One of those whom he introduced to the subject, in 1788, was Alexander von Humboldt, who became a lifelong friend and occasional scientific collaborator. Willdenow greatly extended his educational influence in 1792 with the publication of Grundriss der Kräuterkunde, a basic textbook intended to replace Linnaeus’ obsolete Philosophia botanica 1751). The Grundriss was a great success and long remained a standard text, going through numerous editions in several languages.

Willdenow’s growing reputation brought him membership in the Berlin Academy of Sciences in 1794, and in 1801 he became its principal Botanist. He was named professor of natural history at the Berlin Medical-Surgical College in 1798, at which time he gave up his apothecary shop. In 1801 Willdenow became curator of the Berlin Botanical Garden, which he developed from modest proportions into one of the most comprehensive in Europe, introducing numerous exotic species into its collection. He also continued to add to his own herbarium, which numbered more than 20,000 dried specimens at the time of his death and is still preserved at the Berlin Botanical Garden. In 1810 he was named professor of botany at the new University of Berlin, but he died before formally taking up the duties.

Willdenow lived in an age of worldwide geographical exploration: and although he rarely traveled outside Germany, and never outside Europe, he corresponded with many explorers, who provided him with thousands of botanical specimens for his collections and research. Humboldt, for example, gave him the nearly 400 plants that he collected in Spain in 1799; and it was to Willdenow that he turned for assistance in describing and classifying the thousands of new species that he and Bonpland brought back from their long South American expedition. In 1810 Willdenow traveled to Paris to help Humboldt: but the work was interrupted by an illness that forced him to return to Berlin, where he died in1812. Willdenow also had undertaken a thorough revision of Linnaeus’ Species plantarum,a massive project that was incomplete in five volumes at the time of his death.

Although Willdenow’s own researches were primarily taxonomic, he recognized that plants also fall into distinct geographical groups and advocated the systematic investigation of various regularities of plant distribution. Some aspects of the subject had been treated by earlier botanists, especially Linnaeus and his students; but Willdenow was one of the first to conceive of a separate and clearly historical botanical discipline dealing with plant distribution in relation to climatic, geographical, geological, migrational, and other factors. He discussed this discipline under the heading “History of Plants” in the first edition of Grundriss der Kräuterkunde, and substantially revised and expanded the section in subsequent editions.(The following account is based primarily on the second edition.)

Willdenow understood the scope of the history of plants “to include the influence of climate on vegetation, the changes that plants have probably endured during the revolutions of our globe, the distribution of plants over the earth, their migrations, and finally, the means by which Nature has provided for their preservation.” Under the first heading he included the role of climate in defining the great floral regions of the earth, the climatic adaptations of plant species as limiting factors to their distribution, and the ability of climate to influence the relative number of plant species found in a given region as well as their general characteristics, such as size and shape. In discussing the changes of plants, Willdenow refuted Linnaeus’ theory that new plant species can arise through the hybridization of old ones, and he defended the idea that many species have become extinct over the course of time as a result of geological and climatic change.

Regarding the distribution of species, Willdenow proposed a theory that attempted to relate the present division of the earth into floristic regions to its geological history, as then understood. Accepting the view that the earth was originally covered by a vast sea from which only the highest mountain ranges emerged, he suggested that God had populated these mountain archipelagoes with all the plant species that would ever exist, creating each species in only one place. Then, as the seas receded, the plants descended from the mountains and spread to the surrounding lowlands until they encountered some barrier to further migration. It is because each mountain range had a unique set of species that the earth is still divided into more or less distinct floral regions that cannot be explained through climate alone. As Willdenow demonstrated at length, however, there are numerous means by which plants and their seeds can be transported over even the most formidable barriers, so that considerable mixing of the original floras has occurred and continues to occur. He thus recognized that the present distribution of plants is the result of historical processes and suggested that by studying the present pattern it should be possible to reconstruct both the primeval distribution and the processes that have led to the present one. He himself did not pursue this and other aspects of the history of plants in great detail; but it was partly due to his influence that others, especially Humboldt, went on to establish the field of phytogeography on a comprehensive basis.

BIBLIOGRAPHY

I. Original Works. Willdenow’s principal books include Florae Berolinensis prodromus (Berlin, 1787); Tractatus botanico-medicus de Achilleis (Halle, 1789); Historia amaranthorum (Zurich, 1790); Grundriss der Kräuterkunde (Berlin, 1792; 2nd. ed., 1798), also in English as Principles of Botany (Edinburgh, 1805); Berlinische Baumzucht (Berlin, 1796); Species plantarum, 5 vols.(Berlin, 1797–1810); Anleitung zum Selbststudium der Botanik (Berlin, 1804); Hortus Berolinensis, 2 vols. (Berlin, 1806–1809); and Enumeratio horti regii botanici Berolinensis (Berlin, 1809; supp., 1813). Most of Willdenow’s numerous articles are listed in the Royal Society Catalogue of Scientific Papers, VI, 372–374.

II. Secondary Literature. Willdenow’s friend and colleague D. F. L. von Schlechtendal gave an account of his activities as head of the Berlin Botanical Garden in his intro. to the supp. of the Enumeratio (1813), iii–x; he published a fuller éloge in Magazin für der neuesten Entdeckungen in der gesammten Naturkunde,6 (1814), v–xvi. Also useful are Clemens König, “Karl Ludwig Willdenow,” in Allgemeine deutsche Biographic,XLIII (Leipzig, 1898), 252–254; and Max Lenz, Geschichte der königlichen Friedrich–Wilhelms–Universität zu Berlin, 1 (Halle, 1910), 247–249. John Ise and Fritz G. Lange, eds., Die Jugendbriefe Alexander von Humboldts 1787–1799 (Berlin, 1973); and E. T. Hamy, ed., Letters américaines d’Alexandre de Humboldt (1798–1807) (Paris, 1905), contain a number of important letters from Humboldt to Willdenow as well as many references to him. See also Hanno Beck, Alexander von Humboldt, 2 vols. (Wiesbaden 1959–1961), passim, esp. 1, 16–17, and 11, 65–68; Wolfgang-Hagen Hein, “Alexander von Humboldt und Karl Ludwig Willdenow,” in Pharmazeutische Zeitung,104 (1959), 467–471; and Clemens König, “Die historische Entwicklung der pflanzengeographische Ideen Humboldts.” in Naturwissenschaftliche Wochenschrift.10 (1895), 77–81, 91–98. 117–124(not examined).

Jerome J. Bylebyl