CHAPTER VI 



THE EVOLUTION OF PLANT 

 CLASSIFICATION 



N the earliest European works on 

 natural history — those of the Aristo- 

 telian school — we meet with an attempt 

 to classify the different varieties of 

 plants. It was inevitable that the 

 writers of this school should make such 

 an attempt, since no mind trained in 

 Greek philosophy could be content to 

 leave a science in the condition of a mere chaos of isolated 

 descriptions. At first the most obvious distinction, that of 

 size, was used as the chief criterion whereby to separate 

 the different groups of the vegetable kingdom. In the 

 1 History of Plants' of Theophrastus, we find Trees, Shrubs, 

 Bushes and Herbs treated as definite classes, within which, 

 cultivated and wild plants are distinguished. Other dis- 

 tinctions of lower value are made between evergreen and 

 deciduous, fruiting and fruitless, and flowering and flowerless 

 plants. 



Albertus Magnus, who kept alive in the Middle Ages 

 the spirit of Aristotelian botany, was more advanced than 

 Theophrastus in his method of classification. It is true 

 that he divides the vegetable world into Trees, Shrubs, 

 Undershrubs, Bushes, Herbs and Fungi, but at the same 

 time he points out that this is an arbitrary scheme, since 

 these groups cannot always be distinguished from one 

 another, and also because the same plant may belong to 

 different classes at different periods of its life. A study 

 of the writings of Albertus reveals the fact that he had 



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