I am currently planning out/researching on an experiment which aims to determine the effect of an environmental factor on a phenotype of an organism. I am wondering if there are any plants which are readily available for purchase/common that give different flowers depending on the conditions they endure. For example, a plant that has different colored flowers depending on how much light it gets. Any advice will be greatly appreciated.

Regards,
Shaya E

Hydrangeas (H. macrophylla) produce blue flowers when grown in acidic soil and pink when grown in alkaline soil.  They may not grow quickly enough for your purposes, though.  I am guessing that other plants do the same, maybe quicker-growing ones.  Your best bet is probably to get on the phone to a local garden centre.