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PARTS OF PLANT -STEM

THE   STEM  IS  THE  MAIN  SUPPORTIVE   PART  OF   A  PLANT.  that  grow  above  the  ground .Stem  bear   leaves  (organs  of  photosynthesis ),  which  grow   at  nodes,buds (shots  covered  by  protective   scales), which grow  at  the  stem  tip.9apical  or  terminal   buds) and  in  the  angle   between   a  leaf  and  a  stem (axillary  and  lateral  buds);and  flowers  (reproductive  structures).The  stem   forms   part  of  plant's   transport  system :xylem  tissue   in  the  stem  transports  water   and  minerals  from  the roots to the  aerial   part  of  the  plant ,  and  phloem  tissue transport   nutrients   manufactured     in  the  leaves  to  other part  of  the  plant . Stem tissues   are  also  used  to  store   water  and  food . Herbaceous  (non  woody ) stems  have  an  outer  protective  epidermis  covering a cortex    that  consist   mainly  of parenchyma (packing tissue) but  also   has  some  collenchyma (strengthening tissue).Woody  stems  have  an    outer  protective  layer   of tough   bark  ,  which  is  perforated  with  lenticels (pores) to  allow   gas  exchange .Inside  the  bark  is  a   ring   of  secondary  phloem , which  surrounds   an   inner  core  of   secondary  xylem.

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