* Colorful part of a plant: This could be a flower, a fruit, or even a leaf.

* White powder used for cooking: This is likely a spice.

* Homophones: These are words that sound the same but have different meanings and spellings.

Putting it all together, the answer is probably "flour".

Here's why:

* Flour is a white powder made from ground grains, which are plants.

* Flower sounds the same as flour, making them homophones.

Let me know if you'd like to try another riddle!