CHAPTER 4 



SPERM-EGG INTERACTING SUBSTANCES, III 



The shrubs of Forsythia X intermedia Zabel have two sorts of 

 flowers, which are not found growing together on the same bush. 

 In one the styles are short and the stamens long, while in the 

 other, the styles are long and the stamens short (Plate V). In nature, 

 fertilization only occurs when pollen from a flower with long 

 stamens comes into contact with a stigma on a long style (on 

 another flower), or when pollen from a flower with short stamens 

 comes into contact with a stigma on a short style (on another 

 flower). In addition, and for reasons which are obvious from what 

 has been said, Forsythia is self-sterile. Not only does the pollen 

 from one flower never fertilize the same flower (self-sterility); it 

 also never fertilizes a flower of the same type whether on the same 

 bush or another. Moewus (1949, 1950) claimed to have found that 

 when water extracts of Forsythia pollen and stigmata were mixed, 

 the flavonol, quercetin, was found in some cases and not in others. 

 Table 10 shows which combinations of pollen and stigmata produce 



quercetin and which do not. As the amounts of quercetin formed 

 were small and could not be identified by chemical analysis, 

 Moewus used a biological method of identification, which, being 

 of considerable gametological interest, will be described later. 



Further investigations by Kuhn & Low (19490:) appear to have 

 revealed that pollen from long stamens contained rutin, while that 

 obtained from short stamens contained quercitrin, the yields of 

 these substances from pollen being about 10% in each case. 

 Rutin is found in the petals of both types of flower (Kuhn & Low, 

 19496), in approximately equal quantities; it is only in the pollen 



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