116 



The Ohio Journal of Science [\o\. X\^III, No. 4, 



The final step in the development of sexual dimorphism of 

 the sporophyte is attained in the diecious condition. But here 

 again some species are more definitely diecious. There are 

 very few strictly diecious plants. Diecious sporophytes are 

 isolated developments arising from parallel evolutions scattered 

 from one end of the AnthophA^te phylum to the other. In every 

 instance they are derived from bisporangiate ancestors. In 

 some cases as will be shown below the entire transition may 

 occur in a single genus. 



Fig. IS. A mauirc, d\'ing, slaroinale plant of Cannabis saliva L., gruwil in the 



winter. 

 Fig. 10. A blooming, carpellate plant of Cannabis sativa L. of the same age as 



Fig. 18. 



A good example of a diecious species is the common hemp, 

 Cannabis sativa L. The plants are staminate and carpellate 

 with other differences in the flowers besides the sporophylls. 

 The carpellate plants are more robust and much longer lived. 

 Figures 18 and 19 represent two plants of dwarf size raised in 

 the middle of winter in the greenhouse. The plants photo- 

 graphed were transplanted to pots when mature. These abnor- 



