The Ohio Journal of Science 



Vol. XXI APRIL, 1921 No. 6 



REVERSAL OF THE SEXUAL STATE IN CERTAIN TYPES 

 OF MONECIOUS INFLORESCENCES.* 



John H. Schaffner. 



The sporophyte of those higher plants which have an anti- 

 thetic alternation of generations is usually described by mor- 

 phologists as being nonsexual. This means that the sporophyte 

 generation does not produce gametes directly but spores which 

 develop into the gametophyte generation by ordinary cell 

 division, never showing the property of sexual attraction. It is 

 evident that the term "nonsexual" cannot imply that there can 

 be no morphological difference due to a difference of sexual state 

 in various parts of the sporophyte ; for there is such a difference 

 in all of the living heterosporous plants. It would be mani- 

 festly unadvisable to ascribe the dimorphism of stamens and 

 carpels, for example, to any other properties or qualities than 

 sexual states of the same fundamental nature as those which 

 produce sexual dimorphism in gametophytes and gametes. 



If we consider the sporophyte as "nonsexual" because it 

 does not produce gametes directly but nonsexual spores, we 

 may, nevertheless, consider its cells as all potentially sexual 

 since they give rise farther on in the cell lineage to sexual 

 individuals producing gametes. All homosporous sporophytes, 

 therefore, including those of Liverworts, Mosses, Hornworts, 

 Ferns, Horsetails, and Lycopods, are only potentially sexual 

 and are in a neutral state in respect to sex during their entire 

 life history. No sexual state is ever set up directly in their 

 cells until after the stage of sporogenesis is reached, except in 

 such abnormal species where apospory is present. Every such 

 sporophyte is essentially similar in its morphology to every 

 other sporophyte of the same species. In other words, there is 

 absolutely no sexual dimorphism apparent in any part of the 



* Papers from the Department of Botany, The Ohio State University. No. 

 122. 



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