FIG. 168.--Corolla of _Primula sinensis_ turned back to
show a tubular petal springing from it. One only is shown for the sake
of clearness; they are generally numerous.]

The formation of spurs or spur-like tubes in a quasi-regular manner has
been spoken of under the head of Irregular Peloria, p. 228, but we
occasionally meet with tubular processes which seem to occur in an
irregular manner, and to have no reference to the symmetrical plan of
the flower, and which are due probably to the same causes as those which
induce hypertrophy. Such spurs have frequently been seen on the corolla
of _Digitalis purpurea_, _Antirrhinum majus_,[352] _Tulipa Gesneriana_,
and occasionally on the sepals of _Fuchsia_. They are very frequent in
some seasons in the corolla of certain calceolarias (_C. floribunda_).
By Morren this production of adventitious spurs was called
"Ceratomanie."

[Illustration: FIG. 169.--Corolla of _Calceolaria_, showing irregular
tubular spurs projecting from the lower lip.]

Similar processes may sometimes be seen in the capsules of _Linaria
vulgaris_, as also in the fruits of some of the Solanums, quite without
reference to the arrangement of the carpels, so that their production
seems to be purely irregular.

Morren, as previously remarked, gave the name "Solenaidie" to tubular
deformities affecting the stamens, a term which has not been generally
adopted; the deformity in question is by no means of uncommon occurrence
in some double or partially pelorised flowers, as _Antirrhinum_,
_Linaria_, &c. A similar formation of conical out-growths may frequently
be met with in the fruits quite irrespectively of any disjunction of the
carpels.

=Contortion.=--An irregular twisting or bending of the stem or branches
is by no means of uncommon occurrence, the inducing causes being often
some restriction to growth in certain directions, or the undue or
disproportionate growth in one direction, as contrasted with that in
another. Hence it may arise from insect-puncture, parasitic growth, or
any obstacle to the natural development. Frequently it exists in
conjunction with fasciation, the ends of the branches being curved round
like a shepherd's crook, from the growth on one side being so much
greater than on the other. Sometimes it is a mere exaggeration of a
normal condition; thus, in what are termed flexuose stems the stem
twists alternately to one side or another, frequently in association
with an oblique form of