56 BOTANICAL GAZETTE [yULY 
of the resin parenchyma cells in the more modern types. This 
question will be taken up later when we consider the genera within 
the group Taxineae. 
Much of the controversy in regard to the position of the Taxineae 
has been based on the character of the gametophytes and reproduc- 
tive structures, especially the ovulate cone and the method of 
development of the proembryo. The evidence which I have to 
offer is derived wholly from the study of the anatomical structure 
of the stem and root of various genera in the group. 
There are included in the family Taxaceae of ENGLER and 
PRANTL (4) the genera Phyllocladus, Ginkgo, Cephalotaxus, Torreya, 
and Taxus. In the most recent classification of the group by 
CouLTER and CHAMBERLAIN (2) Phyllocladus is included in the 
Podocarpineae, Ginkgo has been put in a family by itself, and 
the Taxineae include in addition to Taxus, Torreya, and Cephalo- 
taxus, the doubtful New Caledonian genera Acmopyle and Poly- 
podiopsis. Turning our attention to the 3 accepted genera of the 
group, Cephalotaxus, Torreya, and Taxus, I shall attempt to show 
that the Taxineae are the most modern group of the conifers, that 
Cephalotaxus is the most primitive genus of the subtribe and most 
nearly related to the Podocarpineae, that Torreya is intermediate, 
and that Taxus is the most modern genus of the family and repre- 
sents, so to speak, the last word in the evolution of the conifers. 
If we examine a transverse section of the stem of Podocarpus 
totara, we note the presence in great abundance of resin parenchyma 
cells (fig. 1). These parenchyma cells are even more evident in the 
longitudinal section of the stem (fig. 2) as cells which stain densely © 
with haematoxylin due to the presence of resin. These cells are 
narrower than the tracheids and are characterized by thin walls, by — 
the absence of pits, and end walls at right angles to the long axis of 
the cell. 
A section of the stem of Cephalotaxus drupacea (fig. 3) presents 
a very similar appearance to the stem of Podocarpus. That the 
resin parenchyma cells are widely distributed throughout the 
annual rings of the stem is evident from a consideration of the low 
power photograph (fig. 4). The location of these cells is shown by 
the deep staining of the resinous contents. 
