1053 
Botryopteris anti qua, Kidston. 
In some cases it may coexist in the same bundle with the more 
advanced type, i. e. that brought about by the divisions of a definite 
meristem. Thus pseudo-secondary wood is found at the nodes of Proto - 
catamites , where an abrupt increase in the centripetal primary wood takes 
place, but the centrifugal primary wood of the same bundle is added to by 
the agency of a normal cambium (Fig. 35). 
IX. Bearing of the New Observations on the Affinity 
of the Genus. 
In Dr. Paul Bertrand’s admirable monograph 1 on the frond of the 
Zygopterideae, he not only accepts the view that Botryopteris is a reduced 
type, but suggests the mode of its origin. Thus on page 278 he says : 
‘ The Anachoropterideae seem to be derived from the ancient Zygopterideae 
by the loss of the accessory plane of symmetry. The Botryopterideae 
form a series parallel to the Anachoropterideae, from which they are derived 
by the approximation of the two fundamental poles to the anterior face of 
the foliar trace.’ 
If this view be accepted we must interpret the simplicity of structure 
met with in Botryopteris antiqna as due to reduction, and not to its relatively 
primitive character. As already pointed out, this view involves the assump¬ 
tion that the diarch type of petiole is older than the monarch, and the 
species is in process of simplification. This result is not easy to harmonize 
with the fact that later forms of Botryopteris petiole are triarch. 
If we hold Bertrand’s view we must grant that not only do the two 
Anachoropteridean ‘ fundamental poles approximate to the anterior face 
of a foliar trace ’, but that very frequently they are represented by one pole 
only throughout the main rachis of the petiole in the oldest known species 
of the genus (Fig. 14). 
Our new knowledge of the stem structure and nodes of the older 
Zygopteridean Ferns, Metaclepsy dr op sis duplex and Diplolabis Ronieri , which 
we owe to Dr. Gordon, leads us to regard these forms as possessing a less 
specialized type of stem structure than later Zygopteridean species, e. g. 
Ankyropteris corrugata. The nodal form of the petiolar bundle, i. e. the 
leaf-trace, is also comparatively simple, exhibiting in transverse section 
a tangentially extended band of primary xylem with a mesarch protoxylem 
group at either end. This structure appears to offer the best basis of com¬ 
parison between the Zygopterid and Botryopterid types. 
The section of the stem of B. antiqua shown in Fig. 13 a is not unlike 
the type found in Metaclepsydropsis , except that the peripheral larger centri¬ 
fugal elements are continuous all round the periphery in the latter. 
1 P. Bertrand : Etudes sur la fronde des Zygopteridees, 1909. 
3 z 
