Mar., 1911.] 
The Classification of Plants, VI. 
293 
may belong elsewhere. It is believed that the segregation into 
sub-classes, as given below, is essentailly correct and represents 
phyletic developments. In the older arrangements the treatment 
of the series is often very inconsistent, in some cases proceeding 
from the primitive to the specialized, in others from the most 
highly specialized to the most primitive, as in the case of the grass 
family. The arrangement must be inverted beginning with the 
primitive bamboos and ending with such extremely specialized 
genera as Indian corn. 
The sub-classes at present recognized by the writer are as 
follows : 
Monocotylae: 
Helobiae. 
Spadici florae. 
Glumiflorae. 
Liliiflorae. 
Dicotylae: 
Thalamiflorae. 
Centrospermae. 
Calyciflorae. 
Amentiferae. 
Myrtiflorae. 
Hcteromerae. 
Tubiflorae. 
Inferae. 
There can be little question but that the Helobiae represent 
the lowest monocotyls and the Thalamiflorae the lowest dicotyls. 
Any comparative morphology based on phyletic ideas must come 
to this conclusion. The lower types of these two subclasses are 
about on a level. There is little point, therefore, to the discus- 
sions as to whether monocotyls or dicotyls are the higher group. 
Since the highest dicotyls go far beyond the highest monocotyls in 
floral specialization, it is more convenient to place the monocotyls 
first in the list, even though the gametophytes of their highest 
members, the Orchidaceae, probably represent the most extreme 
reduction and specialization. The classification of the vascular 
plants should be based primarily upon the sporophyte. 
Finally, it should be clear that generalizations as to primitive 
conditions and evolutions can not be based upon such extremely 
specialized forms as Welwitschia (Tumboa) , Piperaceae, Casuarina, 
and other peculiar groups. The gametophytes and the minute 
morphology have undergone specialization as well as the more 
exposed parts. 
A general representation of the supposed relationship is given 
in Figure 1. The Helobiae begin with the Alismaceae and related 
forms and end with the Vallisneriaceae which are highly special- 
