FLOWERS 



51 



about the relative positions in the embryo sac as shown in 

 Fig. 23. 



Pollination. — This is a mechanical process in which pollen 

 is transferred from an anther to a stigma. Pollen may be 

 transferred from an anther to the stigma in the same flower. 



pollen iube 



eqg nucleus 



pericarp 

 ouier /niefi/item 

 innerhhijvtneni 



nucellvi-' 

 embrno sac -' 



polarnuc/ei 

 aniipodals 



Fig. 23. — Diagram of a simple pistil as seen in lengthwise section showing a 

 single ovule just prior to fertilization. 



This is termed autogamy or close pollination. Or, pollen 

 may be carried from an anther to a stigma of another flower 

 on the same individual plant. This is called geitonogamy. 

 Again, pollen may be transferred from an anther to a stigma 

 of a flower on another individual plant. This is termed 



