THE PLANT WORLD 



A MONTHLY JOURNAL OF POPULAR BOTANY. 



F. H. KNOWLTON, Ph. D., Editor, U. S. Nationa:. Museum, Washington, D. C. 



ARTICLES AND NOTES ON ANY SUBJECT OF INTEREST TO PLANT-LOVERS ARE SOLICITED, AND SHOULD 



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Some of the users of the more recent manuals of botany express a 

 difficulty in readily ' finding things ; ' that is, having become familiar 

 with the sequence of groups in the older manuals it was easy to turn 

 to well-known forms, while in the late books the arrangement is new 

 and strange and nothing is in its accustomed place. They ask why 

 these changes were made. 



In order to answer this question it will be necessary to give a 

 brief history of botanical classification, for it is a step in this history 

 that is involved. 



Beginning with Theophrastus ( B. C. 371), who divided the 500 

 species of plants known to him into Trees, Herbs and Shrubs; and 

 Dioscorides (A. D. 77 ), who divided all plants into Trees and Herbs, 

 we find that the first attempt at a true classification was made by 

 Gesner of Zurich ( 1516-1565 ), who pointed out the fact that the way 

 to discover the affinities of plants was to study their flowers and seeds. 

 Gesner's work was taken up by Cesalpini in Italy, thirty years later, 

 and the actual foundation of scientific botany was laid. Ray in Eng- 

 land (1682-1703) first established natural orders or families, and 

 Tournefort in France ( 1694-1700 ) first defined genera as we now un- 

 derstand them Linnaeus ( 1753) established binomial nomenclature, 

 and devised an artificial system based on the stamens and pistils which 

 became the accepted arrangement for nearly a century. Linnaeus well 

 recognized the purely artificial nature of his system and attempted to 

 formulate a natural disposition but made a practical failure of it, and 

 it was not until 1789 that a true natural system was worked out by A. 

 L. de Jussieu. He established one hundred orders and arranged all 

 known plants under them, beginning with the most elementary. In 

 T819 De Candolle, another distinguished French botanist, published 

 an arrangement of plants which reversed that of Jussieu, inasmuch as 

 it began with the higher and ended with the lower forms. It is this 

 classification, or some slight modification of it, that has been in use 



