252 PHYSIOLOGICAL BOTANY. PART II. 



fruit. A superabundance of moisture retards the flower- 

 ing, and also affects the formation of flower-buds ; and 

 it is generally observable, that where the functions of 

 nutrition are forced into a state of unnatural excite- 

 ment, the plant has an increased tendency to produce 

 leaf-buds rather than flower-buds. Hence it is re- 

 marked, that when the fruit trees of temperate climates 

 are transplanted to the warm and moist regions of tin- 

 tropics, they frequently become barren, although they 

 continue to push their shoots with vigour. To coun- 

 teract this effect, a practice is resorted to in the East 

 Indies, of laying bare some part of the roots, which 

 checks the growth, causes the leaves to fall, and thus 

 predisposes the plant to form flower-buds instead of 

 leaf- buds. At the period of flowering, the vital energies 

 of the plant seem to be called into extraordinary activity, 

 and the organs of inflorescence are developed with 

 great rapidity. An Agave fvetida which had vegetated 

 in the Paris garden for nearly a century, and during 

 that period had scarcely shown any signs of increase, 

 during a warm summer began to show signs of flowering. 

 In eighty-seven days, it had grown twenty-two feet 

 and a half, and during one portion of this interval it 

 increased at the rate of nearly one foot per diem. 



(248.) Periods of Floirrri lit/. The precise periods 

 at which a species commences flowering in different 

 years, range within certain limits, dependent partly 

 upon the state of the weather ; but it is very difficult 

 to appreciate all the causes which concur in modifying 

 them. It is evident that the annual distribution of 

 temperature produces a marked effect upon the period 

 of flowering, and that this operates more decidedly on 

 those plants which flower in the spring, than on such 

 as flower later in the year. The almond, flowers at 

 Smyrna in the early part of February, in Germany 

 about the beginning of April, and in Christiania not 

 until the beginning of June. The vintage, however, 

 takes place at Smyrna the beginning of September, and 



