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PLANT-LIFE-FERTILIZATION.

FERTILIZATION  IS  THE  FUSION   of male  and  female   gametes (sex cells) to  produce   Zygote (embryo).
Following  pollination   ,  the  pollen  grains   that  contain  the  male  gametes  are  on  the  stigma  ,  some   distance from  the  female  gamete 
(ovum)  inside  the  ovule .To   enable  the  gametes  to meet,  the  pollen  grain  germinates  and  produces  a  pollen  tube  ,  which  grows   down  and  enters    the  embryo   sack ( the  inner  part  of   the  ovule   that  contains  the  ovum).Two     male   gametes  ,  travelling  at  the  tip  of   the  pollen tube ,enter   the embryo   sac .ne  gamete    Ose  with   the   ovum   to  produce   a   zygote that  will  develop  into   embryo     plant  .The   other  male  gametes  fuses  with  two  polar  nuclei   to  produce  the  endosperm  , which  act  as   a  food  store   for  the  developing   embryo.
Fertilization    also  initiate  other  changes  ;the  integument  (outer   part   of  ovule )  forms  a  testa (seed coat) around  the  embryo  and  endosperm , the  petals  falls  off;the  stigma  and  style wither and   the  ovary  wall   forms  a layer (called  the  paricarp)around  the seed .Together   the  paricarp  and  seed   form  the  fruit ,  which  may  be   succulent  or  dry.In  some  species  (e.gatblackberry) ,apomixis   can  occur  ;the   seed  develop  without  fertilization of  the  ovum  by  a  male  gamete    but  


enodosperm   formation   and  fruit   development   takes  place   as  in   other  species.



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