세맥(細脈)=가는잎맥. 측맥과 측맥 사이를 연결하는 가는 엽맥.

맥은 관다발과 싸개(Vascular bundle)로 이루어져있다.
- 물관부(Xylem) : cells that bring water and minerals from the roots into the leaf.
- 체관부(Phloem) : cells that usually move sap, with dissolved sucrose, produced by photosynthesis in the leaf, out of the leaf.
- 싸개(Sheath) : ground tissue made of lignin surrounding the vascular tissue. This sheath has a mechanical role in strengthening the rigidity of the leaf.