U INTRODUCTORY ESSAY.
The ebeatbs in those species with non-cii-riferous leaves, aiid usually jDrovided
with flagella in the upper part of the plant, are without these appendages in the
lower portion, as it seems that the flagella appear only when the plant has acquired
a certain degree of development, the spadices being produced still later. In many
cases in a full grown plant one leaf sheath bears a spadix and the next one a flagellum
and so on : in other instances, such as C. radiakis, C. pachystemonus and C. àigitatus,
every sheath of a fertile and full-grown plant has its own spadix,
VI.-The Leaf.Sheath Flaqella.
The leaf-sheath flagella are sterile or abortive spadices arising from some of
the leaf-sheaths at the point where normally fertile spadices are inserted. We have
conclusive proof that the flagella are no more than incompletely developed spadices
in the fact that we occasionally tind them bearing more or less incompletely
developed spikelets, as not infrequently happens in C. heteroideus. Martius uses the
name " lora" for the flagella, but I have chosen the latter term as being in more
common use and more readily intelligible.
In very many species the spadix, and especially the female one, is prolonged
at its apex into a long slender clawed appendix corresponding exactly to the
apical part of a flagellum, but we must be careful not to mistake this appendix
for a " c i r r u s " which is the corresponding flagelliform prolongation of the leaf rachis.
For notwithstanding the very great similarity of the two kinds of appendages,
especially in the matter of their function and the identity of their armatm-e of
claws, the flagellum has a morphological origin which is quite distinct from that of
the cirrus.
The leaf-sheath flagella of some of the larger species are exceedingly strong
and resistent and are sometimes of very great length ; I have measured one in
C. flagellum which was over 7 metres long. The biological function of the flagella is
that of attaching the individual to neighbouring plants by means of the booked
prickles with which they are armed ; consequently every Calamtis provided with welldeveloped
flagella is undoubtedly scandent. Those Calami that possess flagella are
destitute of cirri at the ends of their leaves; and, on the other hand, those species
viith cirriferous leaves have no flagella, and their spadices are usually
comparatively short, panicled and non-flagelliferous at their apices.
THE LBAF-SHEATH FLAGELLA.
When a Calamus is not decidedly scandent, but is a derivate of species which
climb and therefore possess weH-foi-med flagella, we find that rudimentary flagella
As a rule the«, cirri and flagella, being quite similarly armed with claws, are substitute
organs which take theplace of each other in the function of providing the plant with
means of climbing, but in some species of Group XII, the sheaths have flagella, the
spadices are flagelliferous, and even the leaves are, though usually very imperfectly,
cirriferous; these species seem therefore to have exerted every means in their
power, and that to the utmost extent, to attain a climbing habit.
The flagella, being morphologically identical with spadices and only difEering in
the absence of branches and spikelets, consist of an axial portion clothed with
cylindric closely sheathing spathes and, as in the fertile spadices, have the lowest
or outermost spathe larger and firmer in texture than the subsequent ones, and
actually armed with straight spines.
L-e quite absent from species with an erect stem, such as C. erecius,
C, arloresccns, etc. In the flagelliform species flagella are also usually absent in the
earlier stages of the plant and only make their appearance when the plant has
reached a certain height and begins to produce spadices. In many species, however,
it is found that spadices alternate with flagella.
In those species where the leaves are cirriferous and the spadices are short and
panicled, we observe now and then a rudimentary flagellum; in C. laiifolius, for
example, I have had occasion to note the presence of rudimentai-y flagella, 8-10
cm. in length, filiform, sheathed by quite tubular prickly spathes, while in other
cases the place usually occupied by a spadix is indicated by a small protuberance.
Such rudimentary flagella have remained abortive because it was not natural for the
spadix which they represent morphologically to become flagelliform.
Very probably in the non-flagelliferous Calami the young plants may bear such
abortive flagella ; this I have had an opportunity of noting in C. crioacanthus.
Whether a species be flagelliferous or not may be ascertained from herbarium
specimens oven if the flagella arc actually missing, because if the spadix is
elongated and ends in a well-developed clawed flagelliform appendix, some of the
leafsheatha are almost certainly flagelliferous; on the other hand, if the spadices
be short, compact, panicled and not flagelliferous, most probably the sheatbs are
not flagelliferous and the leaves of the higher part of the plant are cirriferous.
VII.-The Ocrea.
The ocrea of Calami is a tubular stipule, occasionally split into two parts,
bordering the mouth of the leaf-sheaths. In many cases the ocrea is much elongated
and conspicuous, membranous or chartaceous in texture, glabrous or more or
less clothed with hispid hairs or spicules, sometimes even more or less spinous ; not
infrequently it is very short or is reduced to a short ligule in the axil of the
petiole.
Sometimes the ocrea is persistent and clothes the base of the sheath immediatel
y above its own; its chief function seems to be the protection of the younger
parts of the terminal shoot. Most frequently after the expansion of the leaves the
ocrea decays and is lacerated or reduced, to fragments or filaments, scarcely
retaining any trace of its shape; sometimes, being deciduous or of a transitory
nature, its former presence is revealed only by a narrow scarious rim at the
uiouth of the sheath.
In the ilfrican Calami the ocrea is usually rather elongate and tightly clothes
the base of the sheath above its own, but its outer side is more elongated or
produced than that facing the petiole ; in these species, therefore, the ocrea assumes
commonly the shape of the mouth of a beaked flute, and we may term it reversed
Uguliform."