extension disappears, and the uppermost glumes assume the ordinary shape
and form of those organs."

=General remarks on chloranthy and frondescence.=--Moquin remarks with
justice that the position of the flowers on the axis is of importance
with reference to the existence of chloranthy. Terminal flowers are more
subject to it than lateral ones, and if the latter, by accident, become
terminal, they seem peculiarly liable to assume a foliaceous condition.
Kirschleger says, that in _Rubus_ there are two sorts of chloranthy,
according as the anomaly affects the ordinary flowering branches, or the
leafy shoots of the year, the summits of which, instead of developing in
the customary manner, terminate each in one vast and long inflorescence,
very loose and indeterminate, and with axillary flowers.[293]

On the whole, taking in consideration cases of partial frondescence, as
well as those in which most of the parts of the flower are affected,
phyllody would seem to be most common in the petals and carpels, least
so in the case of the stamens and sepals. It is more common among
polysepalous and polypetalous plants than in those in which the sepals
or petals are united together.

The causes assigned for these phenomena are chiefly those of a nature to
debilitate or injure the plant; thus it has been frequently observed to
follow the puncture of an insect. M. Guillard[294] gives an instance in
_Stellaria media_ where the condition appeared to be due to the attacks
of an insect _Thrips fasciata_. Still more commonly it arises from the
attacks of parasitic fungi, _e.g._ _Uredo candida_, in Crucifers, &c.

In other cases it has been observed when the plants have been growing in
very damp places, or in very wet seasons, or in the shade, or where the
plant has been much trampled on. This happens frequently with _Trifolium
repens_. The frequency with which the change is encountered in this
particular species is very remarkable; it is difficult to see why one
species should be so much more subject to the kind of change than
another of nearly identical conformation.

It might at first be supposed that the same causes that bring about the
complete substitution of leaf-buds for flower-buds (see Heterotaxy)
would operate also in the partial substitution of leaves for other parts
of the flower, but it will be seen that the inducing cause, whether
similar or not in the two cases respectively, acts at different times;
in the one case, it