ADAPTATION AND TREATMENT OF COMBRETUM PURPUREUM. 
9 
of temperature which alone is favourable to the formation of bloom. Amongst hothouse 
plants (to which the present remarks specially refer), those of a ligneous or hard -wooded 
structure appear to require 
a stronger heat to develope 
their highest vigour. As a 
general rule, applicable to 
the same class of plants 
under artificial culture, 
whose growth appears per- 
ceptibly checked by a 
diminution of heat, it may 
be expressed as follows: — 
A progressively high tem- 
perature is favourable for 
plants generally, during 
their season of growth, in 
proportion to their slow cir- 
culation of sap, and the 
tardy development of their 
buds, and also for such as 
are dependent for their 
amount of fertility upon a 
rapid and annually re-accu- 
mulated vigour of growth. 
In the former class it will 
at once be seen that the 
genera Combretum, Ron- 
deletia, and the wooded- 
stemmed species of Clero- 
dendron and Gardenia, are 
included ; also the species 
of Brownea, Croton, Elseo- 
carpus, Jonesia, &c. ; and 
as examples of the latter 
are conspicuous, — the gross 
habited species of Cleroden- 
dron, Aphelandra, Poinset- 
tia, Erythrina, iEschynan- 
thus, &c. 
A high temperature becomes an evil only when injudiciously applied, either by its pro- 
traction over-night, or beyond the period when the requisite amount of growth is obtained. 
It is, in fact, an evil of continuance rather than of degree. That instances have been 
recorded of plants, which have been known to bloom remarkably fine after exposure to an 
exceedingly low temperature, as in Combretum, does not in the least invalidate the evidence, 
that a high temperature is generally, if not always necessary, to that renewed vigour of 
growth, which necessarily precedes a natural and healthy expansion of bloom ; and is 
invariably connected with that constitutional vitality, which is equal to successive efforts 
of growth. 
As regards the practicability, of obtaining bloom from plants under peculiarly favourable 
circumstances of low temperature, it should be remembered, that the actual conditions under 
which the preceding growth of such plants has been obtained, materially affects the evidence 
accompanying any given rule of application for obtaining similar results, in the absence of 
a correct knowledge of such conditions. 
There is a well-authenticated and interesting fact related of a large specimen of Com- 
bretum purpureum, planted out in the ground-border of a hothouse, which, for unexplained 
reasons, was left exposed to the severity of an entire winter, by the lights being removed, but 
which on being replaced in the ensuing spring, the plant progressively attained a vigorous 
growth, and expanded its magnificent racemes of bloom during the summer. This most 
remarkable instance of fertility, under circumstances otherwise sufficient to affect its vitality, 
VOL. i. — no. i. c 
