The 4 main types of stomata are categorized based on the arrangement of subsidiary cells surrounding the guard cells. These types include paracytic, tetracytic, actinocytic, and graminaceous stomata.
Stomata Types Explained
Stomata are crucial pores found in the epidermis of plant leaves, stems, and other organs, facilitating gas exchange for photosynthesis and respiration. The classification of stomata into different types is primarily based on the number, shape, and arrangement of subsidiary cells (also known as accessory cells) that surround the guard cells.
1. Paracytic Stomata
In paracytic stomata, also known as rubiaceous stomata, the guard cells are flanked by one or more subsidiary cells on either side, parallel to the long axis of the guard cells. The subsidiary cells may be of the same size or different sizes.
2. Tetracytic Stomata
Tetracytic stomata are characterized by the presence of four subsidiary cells surrounding the guard cells. One subsidiary cell is located at each pole of the guard cells, while the other two are located laterally.
3. Actinocytic Stomata
Actinocytic stomata feature guard cells encircled by a ring of radiating subsidiary cells. These cells give the stomata a star-like appearance.
4. Graminaceous Stomata
Graminaceous stomata, also known as gramineous or poaceous stomata, are commonly found in grasses (family Gramineae). These stomata have dumbbell-shaped guard cells flanked by two subsidiary cells. The subsidiary cells are parallel to the long axis of the guard cells.
| Stomata Type | Description |
|---|---|
| Paracytic | Guard cells flanked by one or more subsidiary cells parallel to their long axis. |
| Tetracytic | Four subsidiary cells surround the guard cells. |
| Actinocytic | Guard cells encircled by a ring of radiating subsidiary cells. |
| Graminaceous | Dumbbell-shaped guard cells flanked by two parallel subsidiary cells (typical of grasses). |
