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PARTS OF PLANTS -LEAVES

LEAVES    ARE  THE  MAIN   SITES  OF PHOTOSYNTHESIS   and  transpiration   (water  loss &nbs p; by   evaporation ) in  plants A typical   leaf   consist  of     a   thin , flat  lamina (blade)  supported  by  a  network   of   veins  , a  petiole(leaf stalk); and  a  leaf  base ,where  the  petiole   join   the  stem  .
Leaves  can  be  classified     as  simple , in  which    the  lamina  is  a  single   unit  ,  or   compound  , in leaflets.Compound   leaves   may  be  pinnate  , with   pinnae  (leaflets)  on  both  sides  of  a  rachis  (main  axis ),or   palmate,  with  leaflets   arising   from   a  single  point   at   the  tip  of  the  petioleLeaves  can   be classified  further  by  the  overall    shape  of  the  lamina ,  and  by    the  shape  of  the lamina's  apex ,margin  and  base.
PHOTOSYNTHESIS

PHOTOSYNTHESIS   IS  THE  PROCESS  by  which  a  plant  make  their  food   using  sunlight,water, and  carbon dioxide .It  takes   place   inside    special  structures   in leaf  cells    called  chloroplasts.The   chloroplasts  contain  chlorophyll  ,  a  green  pigment   that  absorbs   energy   from   sun light .During  photosynthesis  ,  the  absorbed  energy   is  used  to  join   together  carbon dioxide    and  water     to  form  the  sugar    glucose  ,  which  is  the energy   source    for  the  whole  plant  ;oxygen  ,  a  waste  product ,  is  released   in  the  air  .Leaves  are the   main   sites  of  photosynthesis  ,  and  have  various  adaptation    for  that purpose  :flat  laminae,( blades)provide  a  large  surface    for  absorbing   sun light ;stomata ( pores ) in  the  lower  surface   of  the  laminae   allow  gases  (carbon dioxide  and  oxygen )  to  pass  into   and  out  of  the   leaves ;and   an    extensive  network  of veins       bring  water   into  the leaves   and  transport the   glucose produced   by  photosynthesis   to  the  rest  of  the   plant.


 


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