I have observed the outer epidermis of a leaf and the skin of a pea pod under my Foldscope. The samples were taken at different times of the day, and we can see both closed and open stomata, depending on when they were taken.
This is a leaf peel from a rhoeo (Tradescantia spathacea) plant. This plant’s leaves are generally observed in an introduction to school-level microscopy. The sample has been taken late in the evening.
The stomata are pores scattered among the cells, and are closed. A pair of guard cells surrounds each pore.
This is the skin of a fresh green pea pod. The sample has been taken during the daytime, around midday.
Here, the stomata are wide open. Kidney bean-shaped guard cells are seen around the pores.