﻿400 
  

  

  G. 
  R. 
  Wieland 
  on 
  the 
  Cycadophyta. 
  

  

  Cvcadales. 
  

  

  Persistent, 
  dioecious; 
  

   unisexual 
  strobiles 
  of 
  

   increased 
  size. 
  

  

  Hemicvcadales: 
  

  

  I. 
  Specialized, 
  

   often 
  bisexual, 
  

   extinct. 
  

  

  II 
  Generalized 
  , 
  and 
  

   mainly 
  micro-f 
  iorous 
  . 
  

   [Relatively 
  extinct] 
  

  

  Carboniferous:- 
  Cycadoniicales, 
  Medulloseae, 
  Paracycadales, 
  Pro- 
  or 
  Hemiangiosperms 
  

  

  Diagram 
  1. 
  Cycadophyta: 
  Time 
  range 
  and 
  approximate 
  relationship 
  of 
  

   characteristic 
  types. 
  

  

  