mpanula rotundifolia_. "Double flowers"
resulting from dialysis and multiplication of the petals.]

In _Antirrhinum majus_ double flowers of this character sometimes occur;
the outermost corolla is normal, the succeeding ones usually have their
petals separate one from the other; the stamens are sometimes present,
sometimes absent, and at other times petalodic. Similar occurrences may
be met with in labiates and jasmines, and in _Erica hyemalis_.

Mr. W. B. Hemsley has kindly furnished me with flowers of a similar kind
occurring in wild specimens of _Epacris impressa_,[437] and there are
analogous phenomena in the common honeysuckle (_Lonicera Periclymenum_),
in which three corollas and no stamens often occur.

This duplication may either be accounted for on the theory of chorisis
above alluded to, or by supposing that the extra corolline whorl is due
to a series of confluent petalodic stamens; that the latter is the true
explanation, in certain cases at least, is shown by some flowers of
_Datura fastuosa_, in which the second corolla was partially staminal in
its appearance, and bore nearly perfect anthers, in addition to the five
ordinary stamens, which were unaltered either in form or position. Some
partially virescent honeysuckle flowers have a similar structure.

There are other cases of apparent multiplication or duplication, due,
probably, rather to the formation of outgrowths from the petals than to
actual augmentation of their number. These excrescences occur sometimes
on the inner surface of the petals, or of the corolla; at other times on
the outer surface, as in some gloxinias, &c. This matter will be more
fully treated of under the head of hypertrophy and enation.

=Pleiotaxy of the androecium.=--An increase in the number of whorls in
the stamens is very common, especially in cases where the number of
circles of stamens is naturally large. The augmentation of the number of
stamens is still more frequent where these organs are arranged, not in
verticils, but in one continuous spiral line.

In _Cruciferae_ there is always an indication of two whorls of stamens,
and this indication is rendered even more apparent in some varieties
accidentally met with. So in _Saponaria_, in _Dianthus_, and other
_Caryophylleae_, three and four verticils of stamens have been met with.
In _Lonicera Periclymenum_ a second whorl of stamens more or less
petalodic sometimes occurs.

Moquin mentions a variety of _Rubus fruticos