3/4 GENERAL MORPHOLOGY OF PLANTS 



537. Formula for life history of Gymnosperms.* This 

 could be written as follows, beginning with the sporophyte or 

 second generation. 



/Microspore Male Gametophyte sperm \ 



SpOrOphytC<f (pollen grain) (pollen grain tube and contents) J. 



^Macrospore Female 



(beginning of (endosper 



endosperm) 



Fertilized egg Sporophyte, etc. = 



^Macrospore Female Gametophyte egg 



(beginning of (endosperm -with archegonia) 



endosperm) 



_ FE _ s 

 \ ma sp FG e / 



If the formula starts with the beginning of one of the alternating 

 stages and represents the beginning and end of each generation it 

 would stand thus, MC = mother cell of spores. 



2nd Generation isl Generation 



FE- S - MC( . 



\ ma sp FG e 



Endosperm and 

 Pollen Grain 



Diagram No. VI. Illustrating life cycle of a gymnosperm. Course of deve'opment 

 follows the direction indicated by the arrows. Zygote equals fertilized egg. Vegetative 

 multiplication by off shoots. Note the increase of the sporophyte and decrease of the game- 

 tophyte. 



* For reference. 



