Stem of Angiopteris evecta. 503 
later years of its growth. However, from the manner of 
grouping of the young leaves round the apex, this appears 
to be the case. 
The roots vary in length from 14 to 50 cms. with a diameter 
of about 1 cm.; they are for the most part unbranched, but 
some bear a few weak branch-roots at long intervals. They 
are cylindrical in form, with a black wrinkled surface due to 
the drying up of the tissues, and correspond in structure to 
the earth-roots of Russow, possessing, however, in general 
more than five groups of protoxylem. 
The apex of the stem is protected by the circinately coiled 
fronds of the young leaves, each leaf being surmounted by 
those older than itself. 
Turning now to the consideration of the leaves, we find 
that these occur in the older parts of the stem, mainly on 
the upper surface, but a few small ones are also found on the 
under surface, half concealed by numerous roots. 
In the younger parts the leaves are arranged round the 
axis with an approximation to radial symmetry. 
The oldest leaf-bases are more or less shapeless masses, 
owing to decay, but higher up on the stem the leaves display 
a well-marked differentiation into leaf-base and stipules. 
In the lower parts of the leaf-base, the petiole and stipules 
are confluent into one swollen mass, which is united to the 
stem by a narrow base. This narrow lower region widens out 
rapidly into a mass which is convex towards the exterior 
and plane towards the axis of the stem. The leaf-bases, 
however, vary considerably in size and in method of insertion 
on the stem, and often, particularly in the smaller leaves, the 
above-mentioned dorsiventrality of structure is not obvious. 
The stipules become separate from the leaf-base proper 
towards the axis of the stem, and enclose a space, in which 
the young frond is coiled. The partition joining the stipules 
is concave inwards, and closely pressed against it is the convex 
outer surface of a younger leaf. Figs. 3 and 4 show the 
coiled petiole of the leaf with its enveloping stipules seen in 
longitudinal and transverse view. 
