A. Types of Stomata based on Distribution
- Apple or mulberry type: Stomata are found distributed only on the lower surface of the leaves. eg., apple, peach, mulberry, walnut etc. Such leaves are called as hypostomatic type.
- Water lily type: Stomata are distributed only on the upper epidermis of the leaves. eg., water lily, Nymphaea and many aquatic plants. These plants are epistomatic type.
- Potato type: In this type, the stomata are found more on the lower surface (multistomatic) and less on the upper leaf surface (paucistomatic type). eg., Potato, cabbage, bean, tomata, pea etc. Such leaves are called as amphistomatic and anisostomatic type.
- Oat type: Stomata are equally distributed on the both lower and upper surface of the leaves. These leaves are referred as isostomatic type.
- Potamogeton type: In this case, stomata are altogether absent or if present, they are vestigial. eg., Potamogeton and other submerged aquatics. Such leaves are called as astomatic type.
B. Types of Stomata based on Movement
Loftfield (1856) classified three main groups of stomata in accordance with their daily movement:
- Alfalfa Type: The stomata remain open throughout the day and closed all night, eg., peas, bean, mustard etc.
- Potato Type: The stomata will open throughout the day and night except for few hours in the evening, eg., Allium, cabbage, pumpkin, etc.
- Barley Type: The stomata open only for a few hours in a day, eg., Barley and other cereals.
C. Types of Stomata based on Behavior
Considering the behavior of the stomatal movements, five categories have been recognized:
- Photo-active movements: Light directly or indirectly controls stomatal movements. Such stomata remain open during day time and closed in nights (dark).
- Skoto-active movements: Stomata remain closed during day time and open during night. Such cases are found in succulent plants and other CAM Plants.
- Hydro-active movements: In some cases, stomata open due to excessive loss of water from the epidermal cells and close due to turgid conditions of epidermal cells. This is usually found during mid-day.
- Autonomous movements: In certain cases, stomata open and close at a rate of 10-15 minutes showing diurnal or rhythmic pulsation.
- Passive and Active movements: Opening of stomata is considered as active process and closing is the passive process and this is caused by the turgor changes in the guard cells.