Effects of caffeine on plants and animals

     Minerals like potassium are often found alongside caffeine when it occurs in plant sources like coffee beans, and that could help the plant grow faster. Besides, caffeine is used by many plants as an natural insecticide which paralyzes any poor insect unlucky enough to start eating the plant. So, the caffeine itself would be unlikely to have any direct affect on the plant's rate of growth. Larger mammals and primates like humans find it has a minor stimulant effect but in higher doses it acts like the intended insecticide effect, causing tremors, extreme anxiety, muscle problems, tachycardia, and sometimes death. Hence, caffeine is just a insecticide that is mildly stimulating.