114 
J. M. GREENMAN 
the genetic relationship of the larger groups, yet, at the same time, 
attention has been given to the life history of individual species and 
groups of species, and to a discussion of the relationship and phylogeny 
of certain orders, such for example as the Salicales, a group recently 
investigated from an anatomical standpoint by Ruth Holden. This 
author takes objection to the relatively low position assigned the 
Salicales in the Engler and Prantl system ; and she presents anatomical 
evidence, particularly concerning the primitive condition of the wood 
— namely vasicentric parenchyma and multiseriate rays — to show 
that this simple structure is due to reduction. It is interesting to note 
that in this case at least the anatomical evidence in stem-structure is 
supplemented by reduction in floral structure and also by entomo- 
philous pollenation and porogamy. 
Furthermore, it has been maintained, through comparative mor- 
phological studies, that the Fagaceae have been derived from ancestors 
allied to epigynous types of Resales; and it is not unlikely, moreover, 
that a similar genetic relationship may be the case among the Jug- 
landales. Several families of plants, for instance the Araceae in all 
probability represent lines of reduction and in this case possibly from 
some ancestral liliaceous type. It is not inconceivable also that the 
Gramineae may have developed from an ancestral stock allied to the 
present bamboo tribe. Among the dicotyledonous plants the Euphor- 
biaceae is generally regarded as a polymorphous family in which the 
floral structure in several genera has been very much reduced, as for 
example in Acalypha and Euphorbia. 
In such groups as these a more thorough knowledge of the embryol- 
ogy and seedling anatomy would undoubtedly throw light upon gene- 
tic relationship as well as generic affinity. I think the objection taken 
to the relatively low position assigned to several groups in the Engler 
and Prantl sequence is well founded, but we must wait for additional 
morphological evidence and its proper correlation before satisfactory 
change in their position can be made. 
Important as these embryological and anatomical studies are in 
determining genetic relationships, especially of the greater aUiances, 
yet when it comes to a consideration of the relationship of different 
families and to generic affinity, taxonomy can be materially advanced 
by a more thorough knowledge of the floras of the different parts of 
the world. We need also to know more of the life-history of plants 
already recorded and to have our floras more fully represented in 
