THE NATURE OF THE DIECIOUS CONDITION IN 

 MORUS ALBA AND SALIX AMYGDALOIDES.* 



John H. Schaffner. 



In a recent article on "The Expression of Sexual Dimorphism 

 in Heterosporous Sporophytes"t the writer referred to the 

 nature of the sexual development in diecious plants, giving a 

 number of examples of intermediate types of flowers and 

 inflorescences as observed in various diecious species. It was 

 maintained that sexuality as expressed in the sporophyte is a 

 state which in most higher plants arises in the vegetative tissues. 

 It has seemed to the writer that many geneticists have attempted 

 to establish an arbitrary formula to explain sexual phenomena 

 which cannot be applied to the great preponderance of known 

 facts in regard to sex in plants and animals. The simplest sort 

 of observations on a large number of species, especially when 

 they are studied in phyletic series, will plainly indicate that 

 sexuality is quantitative. The state of maleness or femaleness 

 not only varies in degree in different individuals of the same 

 species but also among many independent groups of species. 



Morus alba L. 



To discover something of the nature of dieciousness in a 

 typical plant by mere observation, the writer chose for one 

 study some trees of Morus alba L., the white mulberry, growing 

 on his old home farm in Clay County, Kansas, where about 

 forty years ago a small grove of this species was planted from 

 nursery stock. These plants soon began to give rise to seed- 

 lings scattered along the ravines of the farm and there are now 

 a considerable number of such trees, from ten to thirty years 

 old, available for the study. The trees are all wild seedlings and 

 have had no artificial treatment except that occasionally a limb 

 has been torn down by the wind or removed by the ax and the 

 tops of some have died off because of the dry climatic conditions 

 of the prairie. It is important in such a study to know that the 

 plants have not been grafted in any way. 



Altogether 66 trees were studied while they were in full 

 bloom in the months of May and June. The trees graded from 

 apparently pure carpellate to pure staminate. Of course, the 



* Papers from the Department of Botany, The Ohio State University, No. 107. 

 t Ohio Journal of Science. 18 : 101-125. 



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