| [College of ACES] | [University of Illinois] | [Illinois CES] |
Your question is one that is often asked.
The simple answer is there are many chemicals in leaves that give colour. The most
abundant of these is green. When the green is no longer as abundant the othe colours such as the
reds oranges and yellows are very pronounced.
If you want a bit more of a scientific answer try http://www.esf.edu/pubprog/brochure/leaves/leaves.htm
If after reading this you stil want to know more just post back here and I will happily answer.
Thanks for your Question
Mark