72 Dr Fleming's Remarks on the Defoliation of Trees. 



Art. XII. — Remarks on the Defoliation of Trees. * By the 

 Rev. John Fleming, D. D. F. R. S. E., &c. Communicat- 

 ed by the Author. 



1 he arrangements which prevail in the vegetable kingdom 

 regarding the " Duration of Leaves 11 do not appear to 

 have been studied with so much care as many other subjects 

 connected with the economy of plants. Aristotle knew that 

 some leaves were deciduous, others not. Caesalpinus states, 

 that many trees lose their leaves in autumn when their fruits 

 are perfected, and their buds hardened, while such as retain 

 the fruit long, keep also their leaves, even till a new crop is 

 produced, and longer, as in the fir, the arbutus, and the bay. 

 Linnaeus distributes leaves, in reference to their duration, into 

 decidua, caduca, persistentia, perennia, sempervirentia. Sir 

 James Edward Smith simplifies this arrangement of Linnaeus, 

 and considers leaves as to their age as of two kinds. Semper- 

 virens, evergreen, permanent through one, two, or more win- 

 ters, so that the branches are never stripped, as the ivy, the 

 fir, the cherry laurel, and the bay. Dechluum, deciduous, 

 falling off at the approach of winter, as in most European 

 trees and shrubs. 



It is much to be regretted that the learned botanist last 

 mentioned should have passed over this division of the cha- 

 racter of plants without improving the classification of his 

 master, or expressing himself more consistently with the phe- 

 nomena of nature. A little attention to the subject will con- 

 vince us, that winter is not the proximate cause of the falling 

 of the leaf in many trees ; that many leaves fall off* long be- 

 fore the approach of winter, and that others, which have with- 

 stood its attacks, perish with the warmth of spring. The 

 want of attention to these circumstances, so conspicuous 

 among our systematical writers, and which I have witnessed 

 among well informed practical botanists, may serve as an apo- 

 logy for the following remarks. Perhaps they possess no no- 

 velty to those who are acquainted with the labours of the 

 more recent physiologists. To others, however, they may ap- 

 pear to have a little interest. 



Read before the Royal Society of Edinburgh, December 5th 1825. 



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