PLASTIDS
     are a group of plant cell organelles that have their
own DNA, which is inherited independently from the cell nucleus, and are surrounded by a double membrane.
Most common plastids:
  
proplastids - plant stem cell plastid that gives to all plastids
      
chloroplasts - contain pigment chlorophyll; site of photosynthesis.
      
chromoplasts - contain carotene pigments and are responsible for the
          yellow, orange & reds in flowers and fruits.
      
leucoplasts are devoid of pigments & occur in multiple types
           
amyloplast,- store starch... special amyloplast = the statoliths,
                present in root & shoot tips ... help plant responds to gravity.
           
aleuroplasts - store protein granuales; ex: peanuts
           
elaioplasts - store oils and fats
       
etioplast - a plastid form that doesn't develop due to lack of light