>> My niece is doing a school science project on this subject and has hit a
> dead end in the libraries. Might any of you have an knowledge of this
> topic or know any good resources on the internet where I could find this
>> Thanks in advance.
I don't exactly know the effect on plants, but the effect on growing
seeds is mutagenic. Caffeine can be used to induce mutations in plants
by first soaking seeds in water for about 24 hours and then soaking them
in coffee for a number of hours and then planting.
Growing Edge Magazine has a good article on do it yourself mutations.
Try their website:
Good luck, hopefully some other readers will have more information to