82 SYLVA AMERICANA. 



Natural Decay. 



In the preceding section we have stated the chief of the 

 diseases to which plants are liable, whether from external injuries, 

 or from internal derangement. But although a plant should not 

 suffer from the influence of accidental injury, or from disease, 

 still there will come a time when its several organs will begin to 

 experience the' approaches of a natural decline insensibly stealing 

 upon it, and at last inducing death. For in the vegetable as 

 well as in the animal kingdom, there is a term or limit set, 

 beyond which the individual cannot pass, though the duration of 

 vegetable existence is very different in different species. 



Some plants are annuals and last for one season only, springing 

 up suddenly from seed, attaining rapidly to maturity, producing 

 and again sowing their seeds, and afterwards immediately 

 perishing. Such is the character of the various species of corn. 

 Some plants continue to live for a period of two }^ears, and are 

 therefore called biennials, springing up the first year from seed, 

 and producing root and leaves, but no fruit; and in the second 

 year producing both flower and fruit, as exemplified in the carrot, 

 parsnip and cabbage. Other plants are perennials, that is, lasting 

 for many years ; of which some are called under shrubs, and die 

 down to the root every year ; others are 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 perfection, continuing vigorous for perhaps 

 100 years more, and then beginning to decay. 



But even of plants that are woody and perennial, there are 

 parts which perish annually, or which are, at least annually 

 sepamted from the individual ; namely, the leaves, flowers and 

 fruit, leaving nothing 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 



