s the occurrence of an increased number of glumes in
_Bromus velutinus_ associated with suppression of the flowers.

=Polyphylly.=--As previously explained, this term is here applied to
those cases in which the members of any particular whorl are increased
in number, the whorls themselves not necessarily being augmented.

The simplest cases of this kind are those in which we meet with an
unusual number of leaves in a whorl.

=Increased number of leaves in a whorl.=--This may arise from actual
multiplication, or from lateral chorisis, or fission. The true nature of
the case may usually be ascertained by an examination of the
distribution of the veins of the leaves, or of the fibrous cords of the
stem, by the relative position of the supernumerary organs, &c.

Among plants with normally opposite leaves the following occasionally
produce them in whorls of three:--_Lonicera brachypoda_, _L. Xylosteum_,
_Weigela rosea_, _Cornus mas_, _Vinca minor_, &c.

_Paris quadrifolia_ may frequently be met with five leaves in its whorl,
or even six.[398]

=Increased number of bracts.=--This is not of infrequent occurrence; one
of the most curious instances is that recorded by Mr. Edwards[399] in
_Cerastium glomeratum_, where, in place of the usual pair of bracts at
the base of the head of flowers, there was a whorl of six or eight,
forming an involucre. The flowers in this case were apetalous and
imperfect.

=Polyphylly of the calyx.=--This may occur without any other
perceptible change, while at other times the number of the other parts
of the flower is proportionately increased. In a flower of a plum six
sepals in place of five sometimes exist; a precisely similar occurrence
in the flowers of the elder (_Sambucus_), the _Fuchsia_, and of
_OEnanthe crocata_, may occasionally be met with. In the latter case,
indeed, there are sometimes as many as ten segments to the calyx, and
this without the other parts of the flower being correspondingly
augmented. Among monocotyledons a similar increase is not uncommon, as
in _Tulipa_, _Allium_, _Iris_, _Narcissus_, &c.

In some plants there seems to exist normally much variation in the
number of parts; thus in some species of _Lacistema_ in adjacent flowers
the calyx may be found with four, five, or six segments.

Most of these cases of polyphylly affecting the calyx may be explained
by lateral chorisis or fission.

=Polyphylly of the corolla.=--This may happen in connection with similar