VASCULAR ANATOMY OF THE MEGASPOROPHYLLS 
OF CONIFERS 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 208 
HaNnNAH C. AASE 
(WITH 196 FIGURES) 
Introductory and historical 
The megasporophyll in Coniferales has been the subject of 
much investigation and discussion, as on the interpretation of this 
structure depends to a great extent the views held in regard to 
the relation of living conifers to fossil forms, and the interrela- 
tion of living genera. If the scale in Pinus, the ligule in Araucaria, 
and the epimatium in Podocarpus represent a dorsal outgrowth 
of the bract, there is added a strong argument in support of the 
contention that the conifers have sprung from lycopod stock. 
If the megasporophyll represents a metamorphosed fertile shoot 
and its subtending bract, there exists a suggestive likeness to the 
Cordaitales, in which the presence of bracts on the shoot makes 
its identification as a shoot less difficult. Again, if the scale in the 
Abietineae represents an axillary shoot and the ligule in Araucaria 
represents a dorsal outgrowth, two other possibilities may be sug- 
gested: either the Coniferales have a double origin, or the Cor- 
daitales included not only forms with compound strobili in which 
the scale is a metamorphosed structure, but also forms with simple 
strobili in which the scale is a ligular outgrowth of the bract. All 
these four views are supported by various investigators. Cor- 
relative with the views taken as to the origin of the group as a 
whole are the views as to the interrelation of genera; forms which 
may be considered as progenitors according to one theory may be 
the descendants according to another, or there may exist no 
relation. 
The investigators before 1868 were concerned chiefly with 
gross observations of development and abnormalities. Rather 
277) [Botanical Gazette, vol. 60 
