Figure 3 (IMAGE) Penn State Caption Heavy metals exit cannabis plants through trichomes, which are hairlike structures located on the flowers. Trichomes are important because they store the CBD oil and the tetrahydrocannabinol (THC) that are desired by consumers. Credit Penn State Usage Restrictions None License Original content 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.