14 DIVISION AND HISTORY OF PLANTS. 



rendered their study and cultivation so important and agreeable a3 

 they now are. 



Scarcely 1,500 plants were known from the descriptions of the 

 ancients at the time of the revival of letters ; whereas more than 

 56,000 species are now known, arranged and described. A perfect 

 chaos must have existed in the vegetable kingdom before the labor 

 of scientific men began to display the order by which it is charac- 

 terized. As it was at first obvious that the production of seeds was 

 the great object of vegetation, attempts were made to classify plants 

 by them ; but their uniformity not corresponding with the diversified 

 character of plants, other organs were resorted to for this purpose. 

 The flower was therefore, thought to present the best means of classi- 

 fication ; yet the absence of flowers in numerous plants, with other 

 limits, soon made it necessary for the principal founder of the science 

 of botany, (Linnaeus), to confine his arrangement to the sexual 

 parts of the flower. The principle was thereupon established which 

 at once led the way to the great Linnaan system. 



Plants were divided into two divisions, one having visible sexual or- 

 gans, (phenogamous), and the other invisible sexes, or wanting those or- 

 gans, (cryptogamous.) The first comprehends the first 23 classes of the 

 system, according to the situation of the sexual parts. But objections 

 have been urged against parts of this system by succeeding botanists, 

 and other organs have been considered as necessary, as well as other 

 methods, to complete the arrangement. The second division is based on 

 the anatomy of plants, and may be called chemical botany. It leads to 

 a knowledge of the laws of vegetative life, their physiology, or physiolo- 

 gical botany, which is analogous with the physiology of animals. On 

 this is based a knowledge of the diseases or deformities of plants, or 

 their pathology, which is of great importance in their cultivation, 

 and also in their general distribution, or vegetable geography. 



The history of vegetable science is brief and imperfect. The Greek 

 philosophers having derived their knowledge principally from Asia 

 and Egypt, examined the laws of vegetable life very superficially, 

 from their want of means and their ignorance of chemistry. They at 

 once arrived at general conclusions and asserted that plants possessed 

 rational souls, capable of the mental powers and indicative of the or- 

 ganization of animals. Aristotle, 384 B. C. published his works on 

 natural history, in which he formed a more rational theory, though 

 little corresponding with that of the presently. Theophrastus, the 

 pupil of Aristotle, is said to have been the founder of philosophical 

 botany ; he wrote several works on the subject. Dioscorides compiled 

 a work containing a partial description, particularly of the medicinal 

 qualities of 1,200 plants, in the first year of the Christian era ; and 

 this was the only source of botanical knowledge for fifteen centuries. 

 To this, Persian and Arabian physicians added 200 plants. 



