Leaf Adaptations
All of the three types of plants have adapted their leaves so that they can better maintain the amount of water they have in their system.
Firstly plants that live in aquatic places, hydrophytes usually have large leaves that are nice and flat which are mainly useful for the floatation of the plant. Submerged hydrophytes may have smaller leaves but lots of them to create plenty of surface area for absorption of materials, such as water and sunlight for photosynthesis. A hydrophytes' leaf structure may look a little different to the other types of plants because they have more stomata at the top as well as little or no apparent waxy cuticle on the leaf as losing water is not a problem.
Unlike hydrophytes, xerophytes are plants that have adapted to have leaves with a very small surface area; some xerophytes do not have leaves at all. Take the cactus for example, these plants have spikes as their leaves. Advantages of the spikes are that they have a very small surface area which decreases the loss of water from the plant. Instead of photosynthesis occurring in the leaves like normal, in cacti photosynthesis occurs in the stem.The spikes also act as a defence mechanism to ward off any prey that may come near which will use up their supply of water. Other types of cacti have no leaves at all, only a very waxy outer layer that slows down the loss of water from the plant.
Some xerophytes, like marram grasses (plants on the sand dunes) curl their leaves up, which creates a pit where all of the stomata are together so it prevents the loss of excess water from the plant.2
Lastly, mesophytes are plants that grow in conditions which have a balanced amount of water and sun, therefore the plants don't really need to adapt to suit the conditions like hydrophytes and xerophytes do. However, a physiological adaptation of some mesophytes is the size of their leaves according to the size of the plant in the environment. Some mesophytes grow lower to the ground and are therefore more shaded by other much taller mesophytes. This means that they do not get as much sunlight which is needed for photosynthesis, so they grow their leaves wider to increase surface area to increase the amount of sunlight they receive. "This tall mesophyte is not thinking of the plants below it, but it does have smaller leaves because it has a higher chance of getting sunlight needed for photosynthesis, so he doesn't need to waste energy growing large leaves."1
Firstly plants that live in aquatic places, hydrophytes usually have large leaves that are nice and flat which are mainly useful for the floatation of the plant. Submerged hydrophytes may have smaller leaves but lots of them to create plenty of surface area for absorption of materials, such as water and sunlight for photosynthesis. A hydrophytes' leaf structure may look a little different to the other types of plants because they have more stomata at the top as well as little or no apparent waxy cuticle on the leaf as losing water is not a problem.
Unlike hydrophytes, xerophytes are plants that have adapted to have leaves with a very small surface area; some xerophytes do not have leaves at all. Take the cactus for example, these plants have spikes as their leaves. Advantages of the spikes are that they have a very small surface area which decreases the loss of water from the plant. Instead of photosynthesis occurring in the leaves like normal, in cacti photosynthesis occurs in the stem.The spikes also act as a defence mechanism to ward off any prey that may come near which will use up their supply of water. Other types of cacti have no leaves at all, only a very waxy outer layer that slows down the loss of water from the plant.
Some xerophytes, like marram grasses (plants on the sand dunes) curl their leaves up, which creates a pit where all of the stomata are together so it prevents the loss of excess water from the plant.2
Lastly, mesophytes are plants that grow in conditions which have a balanced amount of water and sun, therefore the plants don't really need to adapt to suit the conditions like hydrophytes and xerophytes do. However, a physiological adaptation of some mesophytes is the size of their leaves according to the size of the plant in the environment. Some mesophytes grow lower to the ground and are therefore more shaded by other much taller mesophytes. This means that they do not get as much sunlight which is needed for photosynthesis, so they grow their leaves wider to increase surface area to increase the amount of sunlight they receive. "This tall mesophyte is not thinking of the plants below it, but it does have smaller leaves because it has a higher chance of getting sunlight needed for photosynthesis, so he doesn't need to waste energy growing large leaves."1
References:
1. Mrs Moore, Level 2 Biology trip to Hamilton Gardens- mesophytes.
2. Read more at Adaptations- Stomata.
1. Mrs Moore, Level 2 Biology trip to Hamilton Gardens- mesophytes.
2. Read more at Adaptations- Stomata.