349 
in the bundle are pitted, while in Fig. 19 all the elements 
seem to be spiral tracheids. 
The pentagonal cells near the bundle are the filamentous 
cells on which the bundle is suspended in the parenchyma. 
Most probably the whole structure, as caused by wrinkling, 
is unique in anatomy, as We have not been able to find refe- 
rences to similar cases in the literature. No mycelium was 
found in these roots. 
The Bud. 
Fig. 16 shows a series of 16 sections, taken 100 y: apart. 
One thing is apparent from this series : the imbricate aestivation 
in the bud, which is the common case in Botrychium, does not 
occur here. Fig. 14 will make this clear. The mode of aesti- 
vation as expressed in this bud has, as far as we are aware, 
never been recorded in the literature; so we propose to call 
this situation ‘‘alternating aestivation”” because of the alter- 
nation of the leaf bases. The series illustrated by Fig. 16 
shows the origin of the pith and the entire absence of leaf 
gaps. This series is reconstructed in Fig. 13. At the Junction 
of two leaf bases, one or more roots are given off without any 
disturbance of the vascular tissue. À cauline ‘stele” could 
not be traced, as there was no vascular tissue immediately 
under the growing point. The pith is nothing but ground 
tissue enclosed between leaf traces. At this place there was 
formed some secondary xylem in the pericycle. The vascular 
structure of this bud shows an aberrant condition; leaf or root 
gaps could not be traced. This would point either to the fact 
that the stele in Botrychium is not a fixed structure, or that 
B. obliquum and B. silacifolium do not show a very close rela- 
tionship in this respect. 
Summarizing, we can say that B. silacifolium shows in the 
mature condition the following peculiarities : 
1. The leaf trace has a typical Osmundaceous character. 
2. The root trace is similar to that found in B. virginianum, 
Recueil des trav. bot. néerl. Vol. XVIII. 1921. 23 
