t is more convenient to group the
metamorphoses in question under the general term Petalody, which thus
includes all those cases in which the organs of the flower appear in the
form of coloured petal-like organs, whether they be true petals or
segments of a coloured perianth. As the morphological difference between
the organs is one of position merely, there is little objection to be
raised to this course, the less so as the term petalody merely conveys
an idea of resemblance and not of absolute identity.

Petaloid coloration of the ordinary leaves, or of the bracts, is
mentioned under the chapter relating to colour.

=Petalody of the calyx--Calycanthemy.=--As with the bracts, so the calyx
in certain instances is naturally coloured, as in _Delphinium_,
_Tropaeolum_, and others. In _Mussaenda_, _Calycophyllum_, _Usteria_, &c.,
one or more of the calyx lobes become enlarged normally. Considered
teratologically, petaloid coloration of the sepals is either general or
partial; in the latter case the nerves retain their green colour
longest. There is in cultivation a variety of the primrose called
_Primula calycanthema_, in which the upper part of the calyx becomes
coloured, so that the flower seems to have two corollas placed one
within the other; a similar thing happens in _Mimulus_, in which plant,
as the calyx is permanent while the corolla is deciduous, the coloured
calyx is a great advantage in a horticultural point of view. Morren[296]
says that in order to produce the fine colour of the calyx of _Primula
officinalis_ (var. _smaragdina_) the Belgian gardeners cut away the
corolla in a very early stage, and that in consequence the colouring
matter proper to the corolla is developed in the tube of the calyx, the
edges of the limb remaining green, the middle of the limb being purple
(_Primula tricolor_).

[Illustration: FIG. 153.--Flower of _Mimulus_, with petaloid calyx.]

Under this head may be mentioned the occurrence of tubular sepals in
place of the ordinary flat ones in _Helleborus olympicus_; only two of
the sepals were thus affected in a specimen recently observed--a third
exhibited an intermediate condition.

The normal coloration of the calyx occurs most frequently in
polysepalous calyces; teratological coloration, on the other hand,
occurs especially in gamosepalous flowers. This assertion is borne out
by the frequency of the change in the plants already mentioned, and also
in the following:--_Campanula pe