Let us take a leaf from a plant well exposed to sun light.
Boil the leaf in methylated spirit over a water bath.It becomes pale-white due to the removal of chlorophyll.Observe the leaf.
Take the leaf carefully from the test tube by using a brush.
Spread the leaf in a petridish and add a few drops of tinture iodine/betadine solution on it.Again observe the leaf.
The presence of starch will be indicated by a blue - black color.