13 More than 20,000 angiosperm species possess non-dehiscent anthers that open through small pores 14 at the anther's tip. These flowers are visited by bees that use vibrations to remove pollen, a 15 phenomenon known as buzz-pollination. However, some floral visitors fail to transfer pollen 16 efficiently, either through a mismatch of flower and insect size, or because they are unable to 17 buz...