Why are the leaves on the smooth leaved elm smooth?

The leaves on the smooth-leaved elm are smooth primarily due to their structure and the absence of hairs or serrations on their surface. This smoothness helps reduce water loss through evaporation, allowing the tree to efficiently manage water resources. Additionally, the smooth surface can aid in photosynthesis by allowing light to penetrate more effectively and can also help in repelling dust and debris, keeping the leaves clean.