SOME REMARKS ON THE PHYSIOLOGY OF 

 SEXUALITY IN PLANTS 



F. W. SANSOME, Ph.D., F.R.S.E., John Innes Horticultural Institution 



At the present time remarkably little is known concerning the 

 physiology of sexual diiferentiation in plants, but it seems 

 profitable, at a Sex Congress, to consider a few of the known 

 facts, in order that comparison may be made with those in 

 animals. 



Plants, unlike most animals, do not have an early differentia- 

 tion of soma from germ track. Differentiation may occur in 

 almost all living tissues of the plant. The soma is not in a 

 separate line of descent from the germ track. Neither does a 

 plant have a hormone mechanism at all strongly developed. 

 Several workers (Riede, Haberlandt, etc.) have suggested that 

 something analogous to hormones in animals is present in 

 plants, but such agents seem to play a negligible part in regard 

 to sex. 



The plant is morphologically well developed sexually. In 

 all plants, with the exception of some of the lowest Thallo- 

 phytes, the gametophyte is morphologically sex differentiated, 

 while the sporophj^es of some species of algae and ferns, and 

 of all higher plants, are differentiated for sex to a greater or 

 lesser degree. 



Sharp (1925) brings out the fact that, as one passes from the 

 lower to the higher plants, there is a tendency for the sexual 

 differentiation to encroach more and more into the morphology 

 of the sporophyte generation. In Sphcerocarpus, where Allen 

 found allosomes, and in some other Bryophytes the gametophytes 

 only are male or female ; the sporophyte is not sexually differen- 

 tiated. In the flowering plants, differentiation into stamens and 

 ovaries is a step in the differentiation of the sporophyte, which 



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