Microscopy of Nature
Vossen R. (xxxx)
Stomata are small openings that mainly occur on the underside of leaves. They are surrounded by specialised cells and they regulate the gas exchange between the plant and it’s environment, the plant is ‘breathing’ through them, as it were. Stomata are very recognizable by the two kidney- or bean-shaped guard cells that regulate the size of the opening. The guard cells are specialised epidermal cells which contain vacuoles that change their shape when water is absorbed due to a process called turgor, causing the stomata to open. The stomata are opened by stimuli like high humidity and bright light. Depending on the plant family, guard cells are often surrounded by so-called subsidiary cells.
As for the morphology of stomata, some different shapes can be distinguished:
● anomocytic: without subsidiary cells
● paracytic: with lateral subsidiary cells oriented parallel with the guard cells
● tetracytic: with both lateral and polar subsidiary cells
Stomata are fascinating objects to study, in each plant they look a bit different or are positioned differently. To observe stomata we need to peel off the epidermis from the underside of a leaf. If you tear a leaf apart, often a small piece of the epidermis will come off. Especially with thicker leaves this works quite well. Easy to begin with are the leaves of Hosta, Prunus laurocerasus (Cherry laurel) and Tradescantia.