Root System Adaptations

Each group of angiosperm have different root systems that are adapted and specialized to living in their habitats.

Hydrophytes root systems are generally not hugely developed unless the plant is exposed to strong currents or tides. In these cases, larger root systems are grown to ensure the plant is securely anchored and is not at risk of being pulled from the soil due to the currents. However hydrophytes in still water such as ponds and lakes, often have very small root systems. This is because the majority of the nutrients the plant needs can be taken from its watery environment. Therefore the primary need for the roots is anchorage. The root systems are grown specifically, depending on the species of plant, as there is no point in wasting valuable energy growing unnecessary roots. For example,  water lilies have small root systems and use their energy to grow large, flat leaves, so that transpiration can occur and water and minerals are able to move through the plant.

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Mesophytes rely on their roots to provide them with anchorage, water and nutrients. As many mesophytes are exposed to a range of weather conditions, anchorage is highly important to ensure plants are supported and can withstand heavy winds and rains. As hydrophytes get both water and nutrients from their roots, it is essential the roots stay embedded in soil, as if they are ripped up because of weather conditions, they will not be able to provide the plant with the resources it needs to live. Unlike hydrophytes, mesophytes don't have continuous access to water and therefore, their roots must be able to supply them with the resources necessary to sustain life. Different species of mesophytes have different root systems, at different times, depending on their environment and water availability. Most mesophytes are planted or begin germination in Spring. During this time, there is typically ample rainfalls which allow new plants to establish themselves and grow their roots, without having to be especially concerned about water conservation. By the time summer approaches, new mesophytes have grown bigger root systems that penetrate the earth and collect moisture from deeper soils. This is essential as the reduction in rain means there is less water available in the top layers of soil. Without these quick growing root systems, new mesophytes wouldn't be able to access water and would most likely die. Older and more established mesophytes such as oak trees have huge root systems which develop over many years. They often spread several metres under the ground. These extensive roots allow the tree to take advantage of any water available in the soil. As water is continually lost via transpiration, it is essential that the tree has enough water to continue with its life processes. The developed root systems allow this to happen. 

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Xerophytes roots are adapted to sucking up as much water as possible and come in a range of forms, depending on the water or moisture available for the plant. Some xerophytes roots grow deep into the soil, in an attempt to maximise the amount of water they have access to. This is crucial as in many xerophytes habitats, there is no rain for long periods of time. This means the top layers of soil stay bone-dry. By having deep and penetrating roots, xerophytes have access to deep "reserves of ground water" (http://books.google.co.nz/books?id=CP0xZFM7ftoC&pg=PT326&lpg=PT326&dq=xerophytes+with+

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Other xerophytes have very shallow root systems; the Saguaro cactus has a root system that is extensive yet shallow. This type of root system allows for these xerophytes to take advantage of any rainfall. They quickly suck up the water as soon as it sinks into the soil, ensuring it collects as much water as possible. The specialised roots systems are adaptations that xerophytes could not survive without. If Acacia trees had a shallow and undeveloped root system like water-lilies, they would immediately die. They would not be able to survive in the arid conditions of their habitat with roots designed solely for anchorage.