In general, leaf is considered to be organs of a plant. However, leaves collectively could be called as a foliage. Different tissues make up an organ. The leaf comprises of different tissues:
The epidermis tissue makes the upper and lower surface of the leaves.
The mesophyll tissue is present in the centre of the leaves and contains chloroplasts.
Vascular tissues, xylem and phloem, are also present in the plant which allow transportation.