sometimes serves to illustrate the morphological nature
of the pistil. Of this the double-flowering cherry is a well-known
illustration, the pistil being here represented by two small foliar
laminae, whose midribs are prolonged with a short style, terminated by an
imperfect stigma. It is usually the basal portion of the pistil, the
ovary, which is thus specially affected, the margins being also often
disunited so as to expose the ovules. These latter organs may be absent
or they may themselves be the subjects of foliaceous development.
Moquin[263] relates having found in the neighbourhood of Montpellier a
flower of a tulip the ovary of which was represented by true leaves,
which bore on their margins the ovules, and thus presented a striking
analogy with the carpels of those Sterculias, like _S. platanifolia_,
which are foliaceous in texture and open very early in the course of
their development. A similar occurrence has also been frequently
noticed in the Columbine and also in _Cruciferae_ and _Umbelliferae_. M.
Germain de St. Pierre mentions an instance wherein the carpels of _Salix
Babylonica_ were converted into two leaves, provided with stipules. All
the flowers of the catkins were similarly changed, so that it became
permanent, and resembled a branch.

[Illustration: FIG. 137.--Rose, in which the axial portion of the flower
was elongated and the carpels were more or less replaced by leaves.]

Substitutions of this kind form the green "eyes" or centres of certain
varieties of _Ranunculus_ and _Anemone_.

In proliferous roses, or in cases where the central axis of the flower
is prolonged, it frequently happens that the pistils are more or less
replaced by leaves. Fig. 137, from a specimen of Dr. Bell Salter's,
given in the 'Gardeners' Chronicle,' shows the passage, from below
upwards, of the ordinary carpels to perfect leaves; the so-called
calyx-tube being completely deficient and the ovaries entirely superior.
Like most similar specimens, this one bears out the notion that what is
called the calyx-tube in roses is really an expansion and dilatation of
the top of the flower-stalk.

[Illustration: FIG. 138.--Cucumber with leaf attached.]

Fig. 138, for which I am indebted to Mr. S. J. Salter, represents a very
singular conformation in the cucumber, described by that gentleman in
'Henfrey's Botanical Gazette,' i, p. 208, and considered by him to be
due to the foliaceous condition of one of the three carpels of w