158 
G. R. WIELAND 
as if plant life would have been best balanced in the phytologic sense if the 
Devonian Pteridophytes and Lepidophytes both sent their quota into the 
gymnosperm complex. In that case some Cordaites (?), araucarians, and 
perhaps some other Coniferophytes would be these Lepidophyte derivatives. 
Cycadales - 
Persistent, dioecious, 
unisexual strobiles 
of increased size. 
Hemicycadales:- 
I. Specialized, 
often bisexual, 
extinct. 
II. Generalized and 
mainly micro-florous 
[Relatively extinct] 
<5 
Carboniferous:- CycadonUcales, Medulloseae? 
Paracycadalcs, Pro- or Hemiangiospcrms 
Fig. 2. Diagrammatic scheme showing the position in geologic time of primitive and 
hypothetic groups related to the cycads and cycadeoids, and their assumed relation to the 
basal angiosperm types. The position of the latter is indicated by the stippled area. 
