64
I
Leaf morphology: cataphyll, scale leaf A
great
many
plants are dimorphic (30), bearing
membraneous
scale leaves in addition to
relatively large foliage leaves intercepting light.
These 'cataphylls' are sometimes devoid of chlorophyll,
and often perform a protective
surrounding vegetative or Fig. 64.
Agave americana
Scale leaves on the extending flowering axis (see Fig for
opposite the Introduction
mature inflorescence).
floral
role
meristems
(64, 62b). Underground stems of rhizomatous plants cf.
commonly bear
87c) which
may
or
scale leaves (65a, e, but
may
not subtend axillary
buds. Successive leaves located along a shoot
may
demonstrate a heteroblastic
from a simple scale elaborate foliage
leaf to a
leaf.
A
series (29c)
more or
less
similar heteroblastic
sequence occurs in relation
to flowering shoots,
the foliage leaves at the proximal end of the inflorescence merging into scale leaves at the distal end. Scale leaves associated
with an
infloresence are termed hypsophylls or
commonly
bracts
and bracteoles
Particularly in monocotyledons, the
shoot (the prophyll 66)
is
more
(62). first
leaf
on a
often represented by a
cataphyll and differs greatly in size and
morphology
to
more
distal leaves
on that
axis.
Scale leaves are typically smaller in size than the
corresponding foliage leaves of a particular plant,
although small
is
a relative term, the protective
scale leaves (bracts) of the inflorescence of
some
palms being massive woody structures over in length.
1
m