390 GENERAL MORPHOLOGY OF THE FLOWER. 
once proved to demonstration by the fact, that in monstrous 
flowers of the Rose, Clover, Primrose (fig. 783), and other 
plants, the sepals are frequently con- 
Fré. 783: verted into true leaves. 
We now pass to the petals, and 
although these in the majority of 
flowers are of a different colour to 
leaves and sepals, yet in their flat- 
tened character and general structure 
they are essentially the same; and 
their analogy to leaves is also proved 
in many natural flowers by the gra- 
dual transitions exhibited between 
them and the sepals. This is remark- 
ably the case in the White Water-lily 
¥ Bette eto Lcaainto (fig. 453); also in the Magnolia and 
true leaves. From Lindley. Calycanthus, where the flowers pre- 
sent several whorls of floral envelopes, 
which so resemble one another in their general appearance and 
colour, that it is next to impossible to say where the sepals end 
and the petals begin. In many other instances, also, there is no 
other way of distinguishing between the parts of the calyx and 
those of the corolla than by their different positions,—the calyx 
being the outer series, the corolla the inner. The analogy 
between petals and leaves is still further shown by the fact, that 
the former are occasionally green, as in certain species of Cubxa, 
in a variety of Ranunculus, and in one of Campanula rapuncu- 
loides ; and also from their being occasionally converted, either 
entirely or partially, into leaves. We therefore conclude that 
petals like sepals and bracts are homologous with leaves. 
The stamen is, of all organs, the one which has the least re- 
semblance to the leaf. Jn describing the structure of the stamen 
we have shown (page 247), however, that the different parts of 
the leaf may be clearly recognised in those of the stamen. We 
find, moreover, that in many plants the petals become gradually 
transformed into stamens. This is remarkably the case in the 
White Water-lily (fig. 453); thus in the flowers of this plant 
the inner series of petals gradually become narrower, and the 
upper extremity of each petal exhibits at first two little swell- 
ings, which, in those placed still more internally, become true 
anthers containing pollen. From the fact that the stamens can 
thus be shown to be merely modified petals, while the latter 
have been already proved to be modified leaves, it must neces- 
sarily follow that the stamens are so also. If we now refer to 
what takes place in many cultivated flowers, we have conclusive 
evidence at once afforded to us of the leaf-like nature of stamens, 
Thus, in what are called double flowers, the number of petals is 
principally increased by the conversion of stamens into petals ; 
hence the number of the latter increases as the former decreases. 
