hort.), &c.

In the case of what are sometimes termed interrupted leaves, the laminar
portions of the leaf are here and there deficient on both sides of the
midrib, leaving small portions of the latter, as it were, denuded and
connecting the segments of the laminae one with the other. This has been
observed amongst other plants in _Veronica latifolia_, _Broussonettia
papyrifer_, _Codiaeum variegatum_ var. _interruptum_ (hort.),
_Scolopendrium vulgare_, &c.[528] (See p. 328.)

In some of the leaves which have been already referred to in
illustration of the inordinate growth of the cellular portions, the
increased development of parenchyma is associated with a contracted
state of the midrib and its branches, producing a puckered appearance of
the leaf, an exaggerated degree of that change which produces what are
termed "folia bullata." In illustration may be cited various species of
_Mentha_, _Perilla_, _Coleus_, _Fagus silvatica crispa_, _Cytisus_,
_Laburnum_ var., and other forms, cultivated in gardens for their
singularity.

Entire absence of the stalk of the leaf occurs normally in sessile
leaves; on the other hand the blade of the leaf is only occasionally
developed in the phyllodineous Acacias, in some species of _Oxalis_,
_Indigofera_, _Lebeckia_, _Ranunculus_, _Bupleurum_, &c.

De Candolle,[529] from a consideration of _Strelitzia juncea_, in which
the petiole alone is developed, was led to the inference that in many
monocotyledonous plants the blade of the leaf was never developed, the
portion present being the sheath or stalk, unprovided with limb. The
correctness of this inference is shown, amongst other things, by the
occasional presence of a leaf-blade in _Strelitzia juncea_ itself.

Occasionally the laminar portions of the leaf are completely wanting,
leaving only the main ribs, as in the case of _Berberis_, while the
adjoining figure (fig. 215) represents an instance of a cabbage wherein
the innermost leaves are represented by thick fleshy cylindrical bodies
corresponding to the midribs of the ordinary leaves. There is in
cultivation a variety of the cabbage which constantly presents this
peculiarity.

[Illustration: FIG. 215.--Inner leaves of cabbage reduced to their
midribs.]

The suppression of one or more leaflets of a compound leaf has already
been referred to at p. 396.

=Abortion of the perianth, calyx, and corolla.=--Illustrations of
partial development in these organs are not rare, under