358 
of six root traces and only two leaf traces. The four lowest 
roots having no accompanying leaves, it can be assumed that 
the first four leaves in this plant were rudimentary just as in 
B. lunaria. 
Fig. 22 gives a reconstruction of the stele. In the oldest 
plant investigated there is still no trace of a cauline 
stele. Bower (4) and Lang (22) assume that there 1s a cau- 
line stele. Campbell (9) denies this on embryological grounds. 
À similar opinion holds West (41) for Danaea. West remarks 
that ‘the convenient descriptive term ‘stele” is here simply 
employed for the common vascular tissue produced by the 
close association of the earlier leaf and root-traces.”" This idea 
can be applied unchanged on the stele both of B. obliquum 
Fig. 38. 
and B. simplex. There is no reason to assume that the stele in 
B. lunaria would prove to be of (partly) cauline origin. Only 
a more detailed anatomy of the root and leaf can make this out 
satisfactorily. 
The Anatomy of the Root. 
The number of the protoxylems is one, two or three. This 
is the common number. This is considerably less than the 
maximum found in B. lunaria, where Poirault (25) counted 
seven proto-xylems. The vascular bundle in a diarch root could 
be traced in a continuous series of sections. In the youngest 
part, the xylem is pronouncedly exarch and consists of several 
reticular or spiral tracheids, before either endodermis or phloem 
appear. At an older stage (Fig. 29) the two proto-phloems 
