The lines on the leaf are called [[1]].

The lines on the leaf are called veins. Veins are present throughout the leaf lamina, which provides support to the leaf structure. Veins are an integral part of the vascular system of plants and contain conducting tissues, including the xylem and phloem.

Xylem is responsible for transporting water and minerals from the roots to other parts of the plant, including the leaves, while the phloem is responsible for transporting the food, such as glucose, produced during photosynthesis in the leaves to other parts of the plant.

In summary, veins on the leaf play a critical role in providing support to the leaf structure, as well as in the transport of water, minerals, and food to various parts of the plant.