The structures present on the underside of leaves of terrestrial plants that help reduce transpiration are?​

They are called Stomatas.

Explanation:

A waxy cuticle covers all aerial surfaces of land plants to minimize water loss. These leaf layers are clearly visible in the scanning electron micrograph. The numerous small bumps in the palisade parenchyma cells are chloroplasts.

You can find this information here: https://courses.lumenlearning.com/wmopen-biology2/chapter/plant-structures/#:~:text=Stomata%20on%20the%20leaf%20underside,palisade%20parenchyma%20cells%20are%20chloroplasts.