Good question Kelly,
Well starch is a plants way of storing sugar. It links all the sugar molecules together to make them more stable, just like a chain.
And plants store this starch in several different places. Some store them in seeds (to help the seeds grow when needed). This is where the starch in wheat and apples. Other plants store starch in things underground known as tubers. These are potatoes, carrots etc….
But some plants don’t need to store energy, either because there is enough sunlight, or because they die and regrow every year.