Many other instances of peloric flowers are on record. Indian cress or
_Tropaeolum majus_ loses the spur in some double varieties and with it
most of its symmetrical structure; it seems to be considered justly as a
peloric malformation. Other species produce such anomalies only from
time to time and nothing is known about their hereditary tendency. One
of the most curious instances is the terminal flower of the raceme of
the common laburnum, which loses its whole papilionaceous character and
becomes as regularly quinate as a common buttercup.
Some families are more liable to pelorism than others. Obviously all the
groups, the flowers of which are not symmetrical, are to be excluded.
But then we find that labiates and their allies among the dicotyledonous
plants, and orchids among the monocotyledonous ones are especially
subjected to this alteration. In both groups many genera and a long list
of species [486] could be quoted as proof. The family of the labiates
seems to be essentially rich in terminal pelories, as for instance in
the wild sage or _Salvia_ and the dead-nettle or _Lamium_. Here the
pelories have long and straight corolla-tubes, which are terminated by a
whorl of four or five segments. Such forms often occur in the wild state
and seem to have a geographic distribution as narrowly circumscribed as
in the case of many small species. Those of the labiates chiefly belong
to southern Europe and are unknown at least in some parts of the other
countries. On the contrary terminal pelories of _Scrophularia nodosa_
are met with from time to time in Holland. Such facts clearly point to a
common origin, and as only the terminal flowers are affected by the
malformation, the fertility of the whole plant is evidently not
seriously infringed upon.
Before leaving the labiates, we may cite a curious instance of pelorism
in the toad-flax, which is quite different from the ordinary peloric
variety. This latter may be considered from a morphologic standpoint to
be owing to a five-fold repetition of the middle part of the underlip.
This conception would at once explain the occurrence of five spurs and
of the orange border all around the corolla-tube. We might readily
imagine that any other of the five [487] parts of the corolla could be
repeated five-fold, in which case there would be no spur, and no orange
hue on the upper corolla-ring. Such forms really occur, though they seem
to be more rare than the five-spurred pelories. Very little is known
about their frequency and hereditary qualities.
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