Snapdragon (image) Institute of Science and Technology Austria Share Print E-Mail Caption In plants such as snapdragons the stigma contains a toxin that stops pollen growth. Pollen in turn produces antidotes to all toxins except for the toxin produced by the "self" stigma. Credit David Field Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.