Flower And Fruit 177

FIG. 113A
Fruiting head of piri-piri
(Acaena sanguisorbae)

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escence, consisting of a great number
of flowers or florets massed together.

Relationships - The raceme is
probably the primitive form of in-
florescence. The panicle may be
regarded as a branched raceme; the
corymb as a raceme in which the
pedicels of the lower flowers have
lenghthened; a spike as one in which
the pedicels have disappearsed; a
catkin one in which, not only have the pedicels
disappeared, but the flowers of certain inflorescences
have lost their male, while those of others have lost
their female organs; the spadix one in which a similar
thing has happened but on the same inflorescence; an
umbel one in which the internode-like intervals of the
penduncle have diappeared, and all the flowers have
been brought to the same level; and finally, a head
is the same thing as an umbel in which the flowers have
become sessile.

A definite inflorescence (Fig. 114) is one in which
the flower at the end of the axis opens first, the next
flower, where present, being produced by the branching
of the peduncle below the first, the third by a branch
produced from the first branch below the second flower,
and so on till the flowering capacity of the shoot is
exhausted. This will best be understood by consulting
the diagrams. The following are the chief definite
inflorescences: -

1. Solitary. This arises when the main axis
produces at its end a single flower and there is no
branching whatever. This is well seen in the tulip
and tea-tree. In the latter the solitary inflorescence
may be terminal, at the ends of short branches, or
axillary, in the axils of the leaves.

2. Cymose inflorescences are definite inflorescences
that branch as indicated above. The branches may be