Johann Jacob Dillenius was a German university professor and botanist who wrote several descriptive works on plants.
Background
Johann Jacob Dillenius was born in 1687, in Darmstadt, Germany. The Dillenius family were civil servants in the state of Hesse who came to Darmstadt at the close of the sixteenth century. Dillenius’ grandfather, Justus Dillenius, was a treasury clerk (Kammerschreiber), but his father trained as a doctor in the university of Giessen; after several interruptions he completed his studies and was granted a medical licentiate in 1681. Dillenius’ mother was the daughter of the clergyman Danile Funk. In 1682 the death of Laurentius Strauss left vacant the chair of medicine in Giessen and Dillenius’ father was appointed. In this academic circle the family name, which had already been changed from Dill to Dillen, was altered to Dillenius.
Education
Johann Dillenius followed in his father’s footsteps, qualifying in medicine at Giessen in 1713.
St. John’s College, Oxford, admitted him to the degree of Doctor of Medicine in 1734.
Career
After a period of practice in Grunberg, Upper Hesse, he was appointed town doctor (Poliater) in Giessen. Meanwhile his passion for botany developed and led to his election to the Caesare Leopoldina-Carolina Academia Naturae Curiosorum under the name “Glaucias.” About this time he contributed several papers on cryptogams to that academy; these show his concern with the study of cryptogamic sexual organs.
Dillenius’ failure to make headway in Germany, despite the great interest in the subject there, was undoubtedly due to his unwise criticism of the system of classification of A. Q. Bachmann (Rivinus), which was widely accepted in Germany at the time. He attacked Bachmann’s system in his Catalogus plantarum circa Gissam sponte nascentium (1719), in which the merits and demerits of the various systems of classification are enumerated with impartiality and justice. Dillenius rightly did not approve of Bachmann’s use of the regularity and number of petals as the basis for his classification and preferred the system of Ray to those of both Bachmann and Toumefort. Of course Ray’s system was not without its faults - and Dillenius did not escape a harsh reply from Bachmann. Needless to say, Dillenius failed in his role of advocate for Ray’s system in Germany.
In England, Dillenius worked on the encyclopedia (or Pinax) of all the names that had been given to each plant, on the plan originally conceived by Gaspard Bauhin. Fortunately for science, Dillenius interrupted this work frequently to undertake more fruitful tasks, the first of which was the editing of a third and last edition of Ray’s Synopsis plantarum. This work brought him into close contact with the small but active circle of British botanists who helped him with it, especially Richard Richardson.
The years 1724 to 1732 were largely occupied for Dillenius with illustrating, engraving plates, and describing the plants in William Sherard’s brother’s garden at Eltham, near London. In this work no love was lost between the proud owner of the garden, James Sherard, and the ardent botanist. James Sherard, who wanted a sumptuous tribute to his glory, was greeted instead with a work of great simplicity, the chief merit of which is its very accurate descriptions and botanical illustrations of exotic plants recently introduced to Europe, especially in the genus Mesembryanthemum. Sherard never paid Dillenius for the materials needed to print the book, and Dillenius reckoned that he lost some £200 over the work.
Dillenius began putting together in Oxford the oriental plants collected by Dr. Shaw, the Oxford botanist. In 1736 he was Linnaeus’ host in Oxford, and in 1741 he published his most important book, Historia muscorum, in which he introduced a new classification of the lower plants (some features of which system are still in use to this day). In his desire to be definitive Dillenius put a prodigious amount of work into this book, which meets the high standards demanded by more modern taxonomy. But it is in the tradition of eighteenth-century British taxonomy and fails to break fresh ground in its approach to the subject or to utilize recent European advances in the knowledge of the sexual organs of cryptogams.
Despite the promise of his work Dillenius was not offered a university post in botany in Germany. It was not until the wealthy English consul at Smyrna, William Sherard, learned of his work that he received an invitation to serve as a full-time botanist, working on Sherard’s Pinax. Dillenius accepted and by August 1721 he was in England. Apparently it was Sherard’s intention to endow the existing chair of botany at Oxford and to see that Dillenius was appointed to it. This could not be realized while Gilbert Trowe occupied the unendowed chair. Dillenius had to wait until Trowe’s death in 1734, by which time Sherard had died also. In the thirteen years which remained to him Dillenius completed his magnificent Historia muscorum (1741) and continued his study of the fungi with the help of his friend George Deering. Neither the projected book on this subject nor Sherard’s ill-fated Pinax was completed, however, when Dillenius died after a fit of apoplexy.
Dillenius was elected a fellow of the Royal Society in 1724 and served as its foreign secretary from 1727 to 1747. He was also a member of the German Academy of Sciences Leopoldina.