In the lotus leaves, the stomata are present only on the upper surface.
Stomata (or stomates) are a tiny pores found in the epidermis of leaves, stems, and other soft aerial part of plants. The size ranges from around 10-14 µm in length and 3-12 µm in breadth. In mesophytic plants, stomata present both on the upper or adaxial surface as well as the lower or abaxial surface of the leaves. In monocots, the number of stomata present on the upper surface is similar to the number in the lower surface of the leaf. On the other hand, in dicots, the number of stomata present on the upper surface is lower than the number of stomata on the lower surface.
Lotus as well as in other aquatic plants, the leaves are float on the surface of the water. In this conditions, stomata are present only on their upper surface of the leaves and helps in exchange of gases between the plant and the atmosphere. In contrast, in completely submerged plants the stomata are absent and gaseous exchange takes plce through the epidermal cells.