Plants and Water: An Evolutionary Model An in depth look at the different types of adaptations plants use to obtain, distribute and conserve water
Why do plants need water? <ul><li>Water is essential for cellular functions of plants and for the process of photosynthesis . </li></ul><ul><li>Most plants are Terrestrial , which means they live on land, and water is a relatively scarce, but necessary commodity in terrestrial ecosystems. </li></ul><ul><li>In order for a plant to survive, it must be able to obtain water, distribute the water molecules to all of its cells, and then conserve the water within its system. </li></ul>
Mechanisms for Obtaining Water <ul><li>Most plants obtain water through their roots and vascular systems </li></ul><ul><li>90% of plants have fungi attached to their roots, which helps to secure more moisture. </li></ul><ul><li>Mycorrhizal fungas is the most popular type of fungi used to help plants obtain more water. It soaks up excess water from the soil into the plant, and in return, the plant gives the fungi the nutrients it needs to survive. </li></ul>
Types of Roots: Fibrous vs. Taproot <ul><li>A F ibrous root is found on plants that grow in warm, dry climates </li></ul><ul><li>Grass and Corn are two good examples of plants that have Fibrous roots </li></ul><ul><li>A Taproot is significant because it plays a dual role for the plants that it is found on: it is a storage organ for excess water AND a water conductor </li></ul><ul><li>A dandelion is a good example of a plant with a taproot </li></ul>
Mechanisms for Distributing Water <ul><li>Plants have a metabolism which speeds up and slows down based on the distribution needs of the plant </li></ul><ul><li>The process of Evapotransirtation , in which the cohesion of water allows the water to move through the xylem , is the main way that water is distributed throughout a plant </li></ul>
Mechanisms for conserving water: <ul><li>All plants have Stomatas , </li></ul><ul><li>pores found on the underside of a leaf </li></ul><ul><li>(surrounded by guard cells) </li></ul><ul><li>that prevent water loss during photosynthesis </li></ul><ul><li>These Stomatas can open and close to ensure that the correct amount of water is retained </li></ul><ul><li>A plants Succulence , or ability to retain water, is affected by the plants leaf size. A broader leaf can retain more water, BUT falls off more frequently. A smaller, thinner leaf retains less water, but remains stable. </li></ul><ul><li>Some plants also have a Thick Cuticle , which is a waxy coating that prevents water loss in their leaves. </li></ul><ul><li>Plants use bulbs and their roots to store water for when liquid water is not available </li></ul>
Epiphytic Plants <ul><li>Epiphytic plants are unique in that they have no roots. This means that they have their own ways of obtaining, distributing, and conserving water: </li></ul><ul><li>They absorb moisture from the air, which is then converted into water </li></ul><ul><li>They also have hair like leaf structures that absorb water from its surroundings </li></ul><ul><li>Some examples of Epiphytic types of plants would be Ferns, Mosses, and Seaweed </li></ul>Fern Moss
Aquatic Plants <ul><li>Aquatic plants function a little differently than others in that they have very poorly developed roots and vascular systems. </li></ul><ul><li>This means it is more difficult for them than it is for other plants to obtain water. </li></ul><ul><li>Lemna, Salvinia and Marselia are all examples of Aquatic Plants </li></ul>Lemna Salvinia Marselia
Insectivorous and Seed Bearing Plants <ul><li>Insectivorous plants are unique in that they use their leaves to capture and digest their prey </li></ul><ul><li>Seed Bearing Plants support organismic evolution </li></ul><ul><li>They have a built in supply of nutrients and are draught resistant </li></ul>The Pitcher Plant is an example of an Insectivorous Plant A Sunflower is An example of A Seed Bearing Plant
Turgor Pressure and Surface Tension <ul><li>Turgor pressure and surface tension occur when water in the center of a cell pushes against the vacuole membrane. </li></ul><ul><li>This puts the cytoplasmic fluid in the cell under pressure, creating a balloon like effect. </li></ul>
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