INFLUENCE OF CLIMATE ON PLANTS. 
133 
speaking, a special comparative amount of agency, to render them of a proper 
character. "Without reference to the actual degree requisite for any species, we 
may state generally that heat, and a copious supply of moisture, will induce a 
vigorous growth ; while a considerably greater relative proportion of heat is 
necessary for promoting floral developments. It is upon this point that practical 
men have generally become confused, and stumbled. Being unable to account for 
the non-development of flowers in otherwise favourable seasons, they have assumed 
that a period of repose is necessary to consummate and elaborate the embryo 
fructiferous organs in the year antecedent to that in which they are evolved ; the 
facts of the case being that either the temperature was too low, or moisture too 
abundant, to admit of maturation being fully performed. 
A very luxuriant growth is adverse to the protrusion of flowers, solely because 
the supply of nutrimental fluids is, in such instances, invariably greater, in propor- 
tion, than the degree of heat which attends it. For this reason, the summer 
immediately succeeding a warm and rather dry one, is always characterized by a 
fine display of flowers, and an abundant crop of fruit. On the other hand, cold 
and moist, or even warm and wet seasons, are as certainly and uniformly followed 
by partial barrenness ; because the nucleus for the ensuing year is not sufficiently 
perfected for the exercise of the fructiferous functions. 
In support of the statements we have advanced, several facts, of frequent 
occurrence, may be adduced. It is an exceedingly common practice in the culti- 
vation of fruit-trees, when their growth is too exuberant, to deprive them of a 
portion of their roots. This is done professedly with the object of checking their 
luxuriance, and rendering them more stunted ; the latter state being considered 
the most fruitful. The good consequences resulting from such treatment consist 
in the imbibition of much less moisture, and a contracted, but especially a more 
mature development ; since an equal intensity of solar influence is exerted on 
the restricted as on the abundant accretions. 
On the same principle, annual plants, and nearly all kinds of fruit-bearing trees, 
are subjected to the process of transplantation. The loss of roots which inevitably 
accompanies this operation, by suspending, or considerably reducing the absorption 
of moisture, ensures such an extreme elaboration and induration of what sap is 
imbibed, that flowers, seeds, or fruits, are ultimately produced more speedily, and 
in much greater liberality. 
The experienced cultivator of exotic plants will likewise be familiar with many 
instances in which all attempts to flower them have proved futile, until he has 
adopted the course of withholding water. We refer principally to such as are 
grown in a lower temperature than they naturally enjoy ; as a greater degree of 
heat is in all cases equivalent to the application of a less quantity of water ; and, 
therefore, this peculiar management is unnecessary if sufficient heat be present. 
Those exotics which are grown in the open air of this country, frequently 
remain for many years without flowering ; and this period is always more 
