Vascular System of Matonia pectinata. 48 1 
while on the right there is a suggestion of it, the lowest pinnule on 
the peripheral side being isolated and much longer than the others. 
It seems difficult to resist the conclusion that the adult frond of 
Matonia pectinata represents a further development of the tendency seen in 
these Gleichenias with compact flabellate fronds. Though growth in length 
of the axes of the frond has been arrested, the extent of lamina borne 
by each frond has been kept, along with the compact habit, by the 
peripheral growth brought about through the retention of the power 
of branching of the outer (lower) member of each successive dichotomy. 
It is interesting to note that the rachis of each ‘ pinna ’ retains at 
its base the characteristic form of the leaf-trace as it leaves the stele 
of the rhizome, though without the final curl, while the sympodium formed, 
on the view just expressed, by the crowded bases of successive members 
of the dichotomizing system, shows a vascular system consisting of a closed 
cylinder with an internal band-shaped vascular strand. This partial 
simulation of the rhizome-type of vascular structure by the sympodium 
is probably due to the exigencies of the crowded insertion of successive 
pinna-traces. 
The form of the frond in the other species of the genus, M. sarmentosa , 
should be mentioned in this connexion. Here the frond possesses a long 
unbranched rachis, continuous with the petiole, and bearing distant groups 
of two, or sometimes three, narrow strap-shaped laminae which reach a length 
of several inches. The members of each group of laminae are inserted on 
a slightly swollen common base, from which often arises a structure like an 
arrested bud. The laminae themselves are often dichotomously branched, 
and then resemble very closely the dichotomizing laminae of the young 
M. pectinata (e. g. as seen in Plate XXXI, Fig. 6). In the only intact 
frond we have seen, the rachis also ends in a similar lamina dichotomizing 
in the same manner. 
The type of branching of the frond of M. sarmentosa is thus clearly 
different from, and appears to be as exceptional as, that of M. pectinata. 
Its morphology is puzzling, though it might possibly be elucidated with 
the help of young plants, which have not yet been seen. The adult frond 
scarcely gives any help with that of M. pectinata , but there is certainly no 
clear indication of derivation from a typical pinnate form. The resemblance 
of the dichotomously branched strap-shaped laminae to those of the 
young M. pectinata is very striking 1 . 
If the above considerations are sound, it follows that the morphology 
of the leaf in M. pectinata furnishes strong confirmation of the suggested 
1 It is of interest to note that the vascular system of the rhizome of M. sarmentosa is organized 
on the same lines as that of a young M. pectinata. Of two fragments which we were able to 
examine both showed the dicyclic arrangement. In one case the second cylinder was protostelic, 
in the other solenostelic. In the second case a dorsal gap in the second cylinder was still open. 
The base of the petiole, however, could not be examined. 
L 1 2 
