Anatomy of the Ophioglosseae . 381 
left-hand group of the diarch plate of Fig. 5 is absent in the 
part shown in Fig. 4, which is consequently monarch \ 
Several series of sections were cut through the bases of 
diarch rootlets in Botrychium Lunaria. They also have 
a monarch region, as seen in Fig. 6. Here the phloem is 
interrupted opposite the protoxylem (px) } but continuous at 
the other side of the stele. A little further out in the same 
rootlet the structure becomes diarch (Fig. 7) 1 2 . The two 
protoxylems are marked px, and the phloem is interrupted 
opposite both 3 . As arranged in the figures, the lower xylem- 
mass of Fig. 7 is the only one present in Fig. 6, while the 
upper one in Fig. 7 has just appeared, and is only represented 
by two tracheides. A comparison of these two sections is 
much more conclusive than the example of Ophioglossum 
pendulum figured. 
It is interesting to notice that these sections (Figs. 6 and 7) 
closely resemble, in the distribution of their xylem, two roots 
of Ophioglossum Bergianum figured by Bower 4 , and described 
by him as monarch and diarch respectively. 
The above facts lead to the conclusion that the rootlet-base 
has in these cases probably become monarch by reduction 
from diarch structure ; one xylem-group being abortive and 
the two phloems joined on the other side where the missing 
xylem-group would be. The monarch structure of the roots 
of Ophioglossum vulgatum may admit of a similar explanation, 
the reduction extending throughout the roots. 
The possibility of these monarch structures being primitive 
must be acknowledged, but what evidence there is points 
rather to reduction. Thus, though the bases of diarch 
1 This cannot be said with absolute certainty until the development in this 
region has been observed. Unfortunately the material obtainable, both in this 
species and in Botrychium Lunaria , did not include any rootlet at the right stage 
for determining the matter developmentally. 
2 F igs. 6 and 7 both represent sections of the free rootlet near its base. 
3 A few of the sieve-tubes in these two sections are difficult to determine, and 
a little doubtful, but the sieve-tubes are at any rate approximately as shown. 
4 Bower, Studies in the Morphology of Spore-producing Members : II, Ophio- 
glossaceae, Figs. 114 and 113. 
