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A TEXTBOOK OF THEORETICAL BOTANY 



two types of organization so distinct that some have doubted if they are 

 really of common descent. 



The chief distinctions may be summarized thus : — 



The Dicotyledons are divided into the Archichlamydeae, in which the 

 perianth segments are free from each other and the Metachlamydeae 



Fig. 782. — Portrait of Marcello Malpighi. 



(Sympetalae), in which the perianth segments are united into a tube, which 

 is regarded as the higher type. It is associated with more advanced pollina- 

 tion mechanisms and with restricted numbers of floral parts, implying a higher 

 reproductive efficiency. For further details of the classification of the 

 Angiosperms see Volume II. 



