Mesophytes
Mesophytes are the most common plants around us and come with various leaf shapes and sizes but generally, they have a large SA:V ratio for their leaves. (MooreMelissa, 2015)
A common Dock leaf is a good example of a plant with mesophytic leaf qualities. Mesophytic leaves are thin and large giving it a large SA:V ratio and the leaves consists of layers of tissues that are specialized to make life processes such as photosynthesis more efficient.
Leaf adaptation of mesophytes are to reduce the rate of transpiration while increasing the rate of photosynthesis.
A common Dock leaf is a good example of a plant with mesophytic leaf qualities. Mesophytic leaves are thin and large giving it a large SA:V ratio and the leaves consists of layers of tissues that are specialized to make life processes such as photosynthesis more efficient.
Leaf adaptation of mesophytes are to reduce the rate of transpiration while increasing the rate of photosynthesis.
It consists of:
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As mesophytes don't live in extreme conditions, they are exposed to both dry and wet conditions and therefore need to balance water in their cells effectively. They do this by controlling the tiny holes on the lower epidermal layer of their leaf called stomata.(MooreMelissa, 2015)
Stomata are essentially holes on the leaves (the bottom layer in the case of mesophytes) surrounded by two guard cells that open or closes the stomata depending on the water balance in the plant and the outside environment. When there is plenty of water to uptake and in the plant and the outside environment is moist, the plant opens its stomata by making the guard cells turgid. This allows gas exchanges to happen which are necessary for the plants survival as gas exchanges are needed for both photosynthesis and respiration but this also allows water to leave the plant via transpiration. When the concentration of water is low in the plant with dry environments, the guard cells closes the plants by going flaccid. This stops water from leaving the plant via transpiration letting the plant maintain a good water balance but stops gas exchanges which will then stop essential life processes like photosynthesis and respiration from happening so the guard cells cannot stay closed for too long. But this is not a serious problem in most mesophytes that they didn’t develop succulent tissues like most xerophytes as there is nearly always water in abundance. (NinErrin, 2015 ) (bitesizeBBC, 2015) |
Still, it has to control the rate of transpiration as there could be droughts or other weather problems. Mesophytic leaves control the rate of transpiration by controlling their stoma and the concentration gradient between inside the leaf and the outside environment.
Stoma are found at the bottom layers of the leaves unlike floating hydrophytes where they are found on the top layer and are not open all the time as they are not completely surrounded by water at all times. Plants and need to have their stoma in a shaded cool place in order to avoid direct sunlight causing evaporation and to lower the concentration gradient between the inside of leaf and the outside environment. There are also hairs on the lower epidermal layer of their leaves around the stoma which condenses/traps water on the underside of the leaf creating a microclimate on the underside of the leaf which essentially dramatically reduces the concentration between the inside and the outside of the leaf reducing the rate of transpiration. However, the microclimate disappears when a wind blows. The leaf also contains lots of stoma on the lower epidermal layer as they do need transpiration to occur as it is the only method of transporting fresh water and minerals around and throughout the plant and is also necessary for cooling the plant. (NinErrin, 2015 ) (MooreMelissa, 2015) (OnlineBiology, 2015) (SterlingTracy, 2015) (bitesizeBBC, Water Balance, 2015)
Stoma are found at the bottom layers of the leaves unlike floating hydrophytes where they are found on the top layer and are not open all the time as they are not completely surrounded by water at all times. Plants and need to have their stoma in a shaded cool place in order to avoid direct sunlight causing evaporation and to lower the concentration gradient between the inside of leaf and the outside environment. There are also hairs on the lower epidermal layer of their leaves around the stoma which condenses/traps water on the underside of the leaf creating a microclimate on the underside of the leaf which essentially dramatically reduces the concentration between the inside and the outside of the leaf reducing the rate of transpiration. However, the microclimate disappears when a wind blows. The leaf also contains lots of stoma on the lower epidermal layer as they do need transpiration to occur as it is the only method of transporting fresh water and minerals around and throughout the plant and is also necessary for cooling the plant. (NinErrin, 2015 ) (MooreMelissa, 2015) (OnlineBiology, 2015) (SterlingTracy, 2015) (bitesizeBBC, Water Balance, 2015)