Affinities of Helminthostachys zeylanica. 423 
by the number of leaf-scars on the dorsal surface, each one 
probably representing an annual period of growth. In one 
instance, however, two fertile leaves were seen on the same 
rhizome, one immediately behind the other, thus proving that 
in Helminthostachys. there may be, sometimes at any rate, 
more than one leaf produced in one season’s growth. 
The rhizome is somewhat compressed dorsiventrally and is 
fleshy ; as it gets older the growing end becomes successively 
thicker until a certain diameter is reached, after which a fairly 
constant thickness is maintained. Naturally, different indi- 
viduals vary somewhat in their degree of development, but 
about 1 cm. may be taken as the average diameter of a well- 
developed specimen, though many stems fall short of this. 
Although normal branching does not occur, new branches 
occasionally arise as adventitious buds upon the older parts 
of a rhizome, and always, so far as we have seen, at a consider- 
able distance from the apex. Indeed it is most common to 
find the buds connected with portions of stein which are 
extremely short, and from which the cortical tissues have 
almost disappeared, indicating perhaps that it is only on 
detached fragments that the buds arise at all. In fact it was 
hoped that the small fragments of the parent stem attached 
to the buds might prove to be tuberous prothallia, but this 
was not the case. It is of interest to note that the young 
leaves formed on these adventitious buds are of a simpler 
form than those found on mature plants. 
The leaves arise, as has already been stated, in two rows on 
the upper surface of the rhizome. The successive leaves are 
thus inclined first to the right and then to the left of the 
median line. Each leaf divides, at the upper end of the petiole, 
into three sterile main branches, which themselves commonly 
branch still further ; and in the case of the fertile leaves, a 
fourth — sporangiferous — branch springs from the adaxial side 
of the petiole at the same level, or slightly below it, at which 
the sterile branches diverge. The leaves are sheathed at their 
bases by remarkable stipular structures which are comparable 
with those occurring in other Ophioglossaceae, and the still 
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