anatomy and phylogenetic position of betulaceae 433 
Summary 
1. That, although the floral anatomy of the Betulaceae may give 
indications of a reduction instead of primitiveness, yet there are 
other facts which must be taken into consideration. 
2. That whether the Verticillatae should or should not be sepa- 
rated from the Amentiferae is not a question of great importance 
from our standpoint. 
3. That the structure of the Verticillatae is either entirely primi- 
tive or so generalized as to include both primitive and advanced 
conditions, thus indicating that the cohort belongs close to the base 
of the dicotyledonous line. 
4. That the closeness of anatomical relationship between the 
Verticillatae and the true Amentiferae gives evidence as to the primi- 
tiveness of the latter. 
5. That the Betulaceae in general show clear evidence of a primi- 
tive aggregation of specialized rays in relation to the appendages, 
and that these rays become subsequently diffused throughout the 
structure of the wood. 
6. That the alders in general present the aggregate condition 
either normally developed or in a state of reduction. 
7. That in the higher members of the Betulaceae (Carpinus, 
Ostrya and Betula) the aggregate condition clearly lies in the evolu- 
tionary background, persisting only in conservative organs and regions 
or recalled by injuries. 
8. That the general internal anatomy of the Betulaceae and espe- 
cially the ray structures supply no proof for and much against their 
being placed anywhere but near the base of the Dicotyledons. 
9. That, finally, unless some new and more conclusive facts to 
the contrary are brought to Hght, the Betulaceae must be ranked in a 
low phylogenetic position. 
In conclusion, the writer wishes to express his thanks to the 
authorities of the Arnold Arboretum for the privilege of collecting 
material with which to carry on this work; and, also, to those who have 
in any way aided. This work has been done in the Phanerogamic 
Laboratories of Harvard University under the direction of Prof. E. C. 
Jeffrey. 
LITERATURE CITED 
Arber, E. and Parkin, J. The Origin of the Angiosperms. Journ. Linn. Soc. Bot. 
38: 29. 1907. 
