Plastids
Plastids are a group of organelles found in plant cells. They all have their own genetic material which is inherited independently from the DNA in the cell nucleus, and they are surrounded by a double membrane.

The most common plastids are chloroplasts which contain the green pigment chlorophyll. There are also chromoplasts which contain carotene pigments and which are responsible for the yellow, orange and red coloration in flowers and fruits. Leucoplasts occur in plant tissues that do not turn green - a common form, the amyloplast, is used to store starch. A specialised form of amyloplasts, the statoliths, are present in root and shoot tips and are involved with the way the plant responds to gravity.


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Note added at 2003-01-20 23:50:15 (GMT)
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http://www.sciencenet.org.uk/database/Biology/Cell_Biology/b...

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Note added at 2003-01-20 23:50:43 (GMT)
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Plastids
By Derek



Plastids are cells that store specific things.
They are large cytoplasmic organelles found in the cells of most plants, but they are not found not in animal cells..
Plastids form small colorless bodies called proplastids.
Once formed certain kinds of plastids can be converted into other types.
For ex. chlorophyll can be synthesized with a leucoplast and light.
There are three plastid categories- Leucoplasts (white or colorless plastids that store starch granules) , Chromoplasts (colored plastids that store pigment molecules) and Chloroplasts which are essential in the photosynthetic process.

http://sln.fi.edu/qa97/biology/cells/cell4.html