54(5 CONSERVATIVE ORGANS. [LECT. X. 



The size of leaves differs very considerably in 

 different species of plants ; but, as has been cor- 

 rectly remarked, " it is not always the largest 

 " plant that has the largest leaf*." The Burdock, 

 Arctium lappa, produces larger leaves than any 

 other British plant ; but these seldom exceed 

 three feet in length, and two and a half in breadth ; 

 whereas the leaves of the Banana, Musa sapien- 

 tium, are sometimes found ten feet in length by 

 two in breadth ; and those of the Talipot Palm, 

 Licuala spinosa, have been known to exceed 

 thirty feet in circumference -^. 



Having now concluded our examination of the 



external or physiognomical characters of leaves, 



we have next to investigate their internal structure 



or anatomy. To pursue this inquiry, however,. 



with advantage, some mode of classifying leaves, 



in reference to their structure, should be adopted. 



As all leaves have more or less affinity, in point of 



structure, to the stems on which they are produced, 



we might adopt the same arrangement that we 



followed in our inquiries into the nature of stems, 



and examine them as they belong to acotyledonous, 



monocotyledonous, and dicotyledonous plants ; but 



the varieties of structure which each of these 



* Keith's Syst. of physiological Bot. i. p. 37. 



t These leaves, which are fan -shaped, when propped up on 

 one side with a pole, serve as a temporary hut or shade to the 

 natives of Ceylon, who sell their merchandise under them. 



