218 PARTS OF THE FLOWER.—ZSTIVATION. 
a centrifugal manner ; while the individual capitula open, as we 
have seen (page 208), their florets from the circumference to the 
centre, or centripetally ; hence, here the general inflorescence 
is definite, and each partial inflorescence indefinite. In Labiate 
plants we have a directly reverse arrangement, for here the in- 
dividual verticillasters open their flowers centrifugally (fig. 393), 
but the general inflorescence is centripetal ; hence the general 
inflorescence is here indefinite, while each partial inflorescence is 
definite. 
Section 2. Or THE Parts OF THE FLOWER; AND THEIR 
ARRANGEMENT IN THE FLOWER-BUD. 
In common language, the idea of a flower is restricted to that 
portion in which its bright colours reside ; but botanically, we 
understand by the flower, the union of all the organs which con- 
tribute to the formation of the seed. We have already stated 
that the parts of the flower are only leaves in a modified condi- 
tion, or rather, the analoques of those organs, or more properly 
homologous formations adapted for special purposes ; and that 
hence a flower-bud is to be considered as the analogue of a leaf- 
bud, and the flower itself of a branch the internodes of which 
are but slightly developed, so that all its parts are placed in 
nearly the same plane. The detailed examination of this theo- 
retical notion of a flower will be reserved till we have finished 
the description of its different parts or organs, when we shall be 
better able to understand it, as well as other matters connected 
with its symmetry, and the various modifications to which it is 
liable. (See General Morphology. ) 
1. PARTS OF THE FLOWER. 
The parts of a flower have been already treated of in a general 
manner. (See page 17.) But before describing them in detail 
we must treat of their arrangement in the flower-bud—that is, 
of estivation. 
2. ESTIVATION OR PREFLORATION. 
As the general arrangement of the rudimentary leaves of the 
leaf-bud is called vernation (the spring state), or prefoliation, so 
the mode in which the different parts of the flower are disposed 
in the flower-bud is termed their estivation (the summer state), 
or prefloration. The various modifications of eestivation are 
generally the same as those of vernation, and the terms employed 
in describing them are therefore similar: but the former pre- 
sent some peculiarities, which renders it necessary for us briefly 
to refer to their different arrangements. The terms used in 
gestivation especially refer to the relative positions of the com- 
