Moldenhawer, Johann Jacob Paul

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(b. Hamburg, Germany, 11 February 1766; d. Kiel, Germany, 22 August 1827)

plant anatomy.

Moldenhawer was one of the principal founders of plant anatomy. His chief work, published in 1812, reflects substantially the extensive knowledge acquired in this field during the period 1800–1830. During these years, which were characterized by a wealth of polemical tracts on the structure of the basic plant organs, he went his own way in his research and in his studies.

Moldenhawer was the son of the theologian and preacher Johann Heinrich Daniel Moldenhawer and his third wife. He studied theology, following the example of his elder brother, Daniel Gotthilf, a distinguished scholar of Greek and oriental languages and of dogmatics. Moldenhawer lived with his brother both as a student in Kiel until 1783 and in Copenhagen, where he was a candidate in theology. It is not known when he turned to the study of science, a change concurrent with his interest in literature, but it was probably in the mid-1780’s. He was especially attracted to botany. Evidence of Moldenhawer’s interest in these two areas is provided by his first publication, Tentamen in historiam plantarum Theophrasti (Hamburg, 1791), a philological study of Peripatetic botany based on ancient sources. On 13 April 1792 Moldenhavver was appointed extraordinary professor of botany and fruit-tree culture at the Faculty of Philosophy of the University of Kiel. He also lectured regularly on classical Greek literature, especially Pindar. He was able to do this because of his philological training while a theology student.

The scene of Moldenhawer’s most important work was the fruit-tree nursery in Düsternbrook, near Kiel, which was associated with his professorship and which was run by Moldenhawer with great conscientiousness. He botanized only occasionally and directed work at the nursery toward applied botany, especially phytotomy, his major interest. Through use of the nursery, its library, and its five microscopes, Moldenhawer was able to produce his Beiträge zur Anatomie der Pflanzen (Kiel, 1812). This lifework, prepared over eighteen years of unremitting research, is notable for its critical insights and methodical observations.

The Beiträge contains important findings concerning plant anatomy that were made possible by a preparation method of Moldenhawer’s own devising. He allowed the cells and vessels, which he recognized as structural elements, to macerate by decaying in water, then separated out the parts to be examined. His success was attributable to his use of the monocotyledonous corn plant as a subject of investigation and demonstration because of its simple structure and quick growth. The illustrations surpassed all earlier representations of plant anatomy. They included the first accurate depictions of the structure of the disputed fissured openings of the epidermis. By completely isolating the cells and vessels in his preparations Moldenhawer demonstrated that the cell wall is closed on all sides. This discovery clarified a long-contested question, since the membrane was seen to be doubled between two closely packed cellular spaces in intact tissue. Moldenhawer’s later reputation was diminished primarily because he assumed, incorrectly, that cells and vessels were held together by a fibrous network. This assumption, all the more misleading because of his mistaken nomenclature, was in accord with Grew’s hypothesis. On the other hand, Moldenhawer devised the concept of the vascular tissue (Gefässbündel), opposing it to that of the parenchyma. Herein lay his greatest achievement; with this radical new histological orientation he created the foundation of the theory of secondary thickening of woody stems, thereby separating himself most strikingly from the ideas of his predecessors (Grew, Malpighi) and contemporaries (Mirbel). Unfortunately, he never carried out his intention, expressed in 1812, of publishing a detailed work on the structure and development of the spiral vessels, one of his favorite objects of study.

In 1795 Moldenhavver married Catherina Dorothea Gädechens. They had one daughter, Pauline Mathilde, born in 1803. The family lived in Brunswick and later in Düsternbrook. Widely known and honored as a botanist, Moldenhawer was awarded ihe Danebrog Order in 1813 and was named king’s counsel in 1824. He received a further honor in 1821, when H. A. Schrader named a legume genus Moldenhawera. Through a bequest of his daughter (1845) the botanical gardens oi the University of Kiel received Moldenhawer’s herbarium, which encompassed 120 files of plants arranged according to the systems of Forskål, Förster, and Linnaeus.


Mokienhawer’s two major works are mentioned in the text. See the obituary in Neuer Nekrolog der Deutschen, V, pt. 2 (Ilmenau, 1829); and the article in Allgemeine deutsche Biographie, XXII (Leipzig, 1885). For the report on his daughter’s bequest to the University of Kiel, see Botanische Zeitung, 3 (1845), 262; and Prahl (cited below), II, 38.

For works about Moldenhawer see J. H. Barnhart, The New York Botanical Garden. Biographical Notes Upon Botanists (Mschr.), II (Boston, 1965); C. Harms, Lebenbeschreibung (Kiel, 1851); E. Hofmann, “Philologie,” in Geschichte der Philosophischen Fakultät, pt. 2, K. Jordan and E. Hofmann, eds., Geschichte der Christian-Albrechts-Universität Kiel-1665–1965, V (Neumünster, 1969); P. Knuth, Geschichte der Botanik in Schleswig-Holstein (Kiel Leipzig, 1890–1892); M. Möbius, Geschichte der Botanik (Jena, 1937); and F. Overbeck, “Botanik, in’ Geschichte der Mathematik, der Naturwissenschaften und der Landwirtschaftswissenschaften, K. Jordan, ed., Geschichte der Christian-Albrechts-Universität Kiel 1665–1965, VI (Neumünster, 1968). See also P. Prahl, ed., Kritische Flora der Provinz Schleswig-Holstein, des angrenzenden Gebiets der Hansastädte Hamburg and Lübeck and des Fürstentums Lübeck, 2 vols. (Kiel, 1888–1890); H. Röhrich, “Memoria horti medici Academiae Kiliensis III,” in Schleswig-Holsteinisches ärzteblatt, 18 (1965), 376–382; J. Sachs, “Geschichte der Botanik vom 16. Jahrhundert bis 1860,” in Geschichte der Wissenschaften in Deutschland, XV (Munich, 1875); F. Volbehr and R. Weyl, in R. Bülck and H. J. Newiger, eds., Professoren und Dozenten der Christian-Albrechts-Universität zu Kiel 1665–1954, 4th ed. (Kiel, 1956); and O. F. Wiegand, Bibliographie zur Geschichte der Christian-Albrechts-Cniversität Kiel (Kiel, 1964).

JÖrn Henning Wolf