Hydrophytes
Leaves of hydrophytes are the site of photosynthesis and in order for photosynthesis to occur, the plant needs water, sunlight and oxygen. Water is obtained via osmosis from the surrounding directly into the plant cells as a great amount of surface area of the plant is in contact with the surrounding water.(NinErin, 2015 )
Leaf adaptations of hydrophytes are to increase the rate of both osmosis and transpiration.
Leaf adaptations of hydrophytes are to increase the rate of both osmosis and transpiration.
Submerged Hydrophytes
Submerged plants like elodea have highly dissected or thread-like leaves that are flexible which gives the plant a large SA:V ratio making osmosis more efficient and to decreases resistance to the moving water/ current. They also achieve a high SA:V ratio by having only one or two cell layers in their leaves making the leaves thinner. Submerged hydrophytes lake the protective tissues found on land plants i.e. the cuticle as this would make it harder for water molecules, carbon dioxide, oxygen and other nutrients to move into the plant via osmosis/diffusion. They also don’t lack stomata as transpiration cannot occur (outside environment has a higher concentration gradient of water than inside of the leaves) (NinErrin, 2015 ) (MediaDigital, 2015)(SinghKalpana, 2015)
Submerged plants like elodea have highly dissected or thread-like leaves that are flexible which gives the plant a large SA:V ratio making osmosis more efficient and to decreases resistance to the moving water/ current. They also achieve a high SA:V ratio by having only one or two cell layers in their leaves making the leaves thinner. Submerged hydrophytes lake the protective tissues found on land plants i.e. the cuticle as this would make it harder for water molecules, carbon dioxide, oxygen and other nutrients to move into the plant via osmosis/diffusion. They also don’t lack stomata as transpiration cannot occur (outside environment has a higher concentration gradient of water than inside of the leaves) (NinErrin, 2015 ) (MediaDigital, 2015)(SinghKalpana, 2015)
Floating Hydrophytes
Floating plants like water lilies have their leaves floating on the surface of the water. These leaves are tough to withstand weather like rain and water movements. Because the leaves are the only parts of the plant that is well-lit, they contain chlorophyll that captures light energy(photons) needed for photosynthesis and their flat and large structure gives it a big SA:V ratio that helps it to float and absorb both sunlight and water. The stomata are found only on the top surface of the leaves which are open all the time as water loss is not a problem. It is actually important and even crucial that transpiration occurs so that fresh water and with it the dissolved minerals, are able to enter the plant as if the concentration gradient of water is too high within the plant, nutrients wouldn’t be able to be gained via osmosis/diffusion. These stomata are only found on the upper epidermal layer of the plant as if they are not needed on the bottom layer of the plant as dissolved minerals and gases can diffuse straight in without the help of stomata where the surface of the plant is in contact with the water. The leaves have a thin or thick layer of cuticle, depending on their habitat on the top surface of the leaves in order to keep water from clogging the stomata as the stomata need to be clear for gas exchanges. These layer of cuticle is not found at the bottom of the plant as it would disturb the process of diffusion and osmosis which is how most plants gain their nutrients making it inefficient. (NinErrin, 2015 ) (BarnesEric, 2015) (HenryEllen, 2015)
Floating plants like water lilies have their leaves floating on the surface of the water. These leaves are tough to withstand weather like rain and water movements. Because the leaves are the only parts of the plant that is well-lit, they contain chlorophyll that captures light energy(photons) needed for photosynthesis and their flat and large structure gives it a big SA:V ratio that helps it to float and absorb both sunlight and water. The stomata are found only on the top surface of the leaves which are open all the time as water loss is not a problem. It is actually important and even crucial that transpiration occurs so that fresh water and with it the dissolved minerals, are able to enter the plant as if the concentration gradient of water is too high within the plant, nutrients wouldn’t be able to be gained via osmosis/diffusion. These stomata are only found on the upper epidermal layer of the plant as if they are not needed on the bottom layer of the plant as dissolved minerals and gases can diffuse straight in without the help of stomata where the surface of the plant is in contact with the water. The leaves have a thin or thick layer of cuticle, depending on their habitat on the top surface of the leaves in order to keep water from clogging the stomata as the stomata need to be clear for gas exchanges. These layer of cuticle is not found at the bottom of the plant as it would disturb the process of diffusion and osmosis which is how most plants gain their nutrients making it inefficient. (NinErrin, 2015 ) (BarnesEric, 2015) (HenryEllen, 2015)
Common Features
Both floating and submerged hydrophytes have extensive air spaces in their aerenchyma tissues which contains lacunae. Lacunae are extensive air spaces found in the tissues of leaves, stems, and roots of hydrophytes. Lacunae are storage spaces for oxygen that is produced by the plant via photosynthesis that is not diffused but stored to be used in respiration. It is also used for the transportation of oxygen to surrounding living tissues. It acts as a diffusion pathway for the oxygen and as it is filled with oxygen which is less dense than water, it provides buoyancy to the plant. Because it provides buoyancy, lacunaes are less developed in submerged hydrophytes than floating hydrophytes.(HenryEllen, 2015) (BarnesEric, 2015) (Pearson, 2015) (NinErrin, 2015 )
Both floating and submerged hydrophytes have extensive air spaces in their aerenchyma tissues which contains lacunae. Lacunae are extensive air spaces found in the tissues of leaves, stems, and roots of hydrophytes. Lacunae are storage spaces for oxygen that is produced by the plant via photosynthesis that is not diffused but stored to be used in respiration. It is also used for the transportation of oxygen to surrounding living tissues. It acts as a diffusion pathway for the oxygen and as it is filled with oxygen which is less dense than water, it provides buoyancy to the plant. Because it provides buoyancy, lacunaes are less developed in submerged hydrophytes than floating hydrophytes.(HenryEllen, 2015) (BarnesEric, 2015) (Pearson, 2015) (NinErrin, 2015 )