506 CASUALTIES OF VEGETABLES. CHAP. XII. 



which some are called under-shrubs, and die down 

 to the root every year; others arc called shrubs, 

 and are permanent both by the root and stem, but 

 do not attain to a great height or great age ; others 

 are called trees, and are not only permanent by 

 both root and stem, but attain to a great size and 

 live to a great age. The Oak-tree in particular is 

 remarkable both for its longevity and size, being 

 at least 100 years before it attains to its utmost per- 

 fection, continuing vigorous for perhaps 100 years 

 more; and then beginning to decay. The inir 

 mense Oak at Colethorpe, near Wetherby, is said 

 to have exhibited symptoms of decay even in the 

 reign of Queen Elizabeth, 



But even of plants that are woody and perennial, 

 there are parts which perish annually, or which are, 

 at least annually separated from the individual ; 

 namely, the leaves, flowers, and fruit, leaving no- 

 thing behind but the bare caudex which submits 

 in its turn to the ravages of time, and ultimately 

 to death. Hence the ground of a division of the 

 subject exhibiting, first, the phenomena of the 

 decay of the temporary organs, and secondly, the 

 phenomena of the decay of the permanent prgans^ 

 and consequent death of the plant, 



SUBSECTION I, 



Decay of the temporary Organs. The decay 

 of the temporary organs which takes place annually 



