Xerophytes In hot conditions particularly hot, dry and breezy conditions-water will evaporate from the leave surfaces very quickly. A specialized group of plants called xerophytes that survive in very hot and dry regions Ways of conserving water A thick waxy cuticle= in most plants water loss by transpiration is through the cuticles. A thick waxy cuticle minimises water loss. Common in evergreen plants and helps them to survive hot dry summer and cold winter when water is difficult to absorb. Sunken stomata= Stomata located in pits, which reduces air movement, produces a moist air that reduces water vapours potential gradient and also transpiration. Reduced number of stomata= reduces their water loss by transpiration. Reduced leaves= by reducing leaf area, water loss can be reduced. Narrow leave shave a reduced SA: V ratio minimising the amount of water lost in transpiration. Succulents= Store water in specialised tissue in their stem and roots. Water is stored when it is in plentiful supply and then used in times of drought. Hydrophytes Plants that live in water (submerged, on the surfaces or at the edges of the bodies of water) Important that the leaves float so they are near the surface of the water to get light for photosynthesis) Water logging is a problem, the air spaces needs to be full of air not water. Adaptations Very thin or no waxy cuticles= do not need to conserve water as there is plenty available Many always-open stomata= Maximises the number of stomata maximises gaseous exchange. There is no risk to the plant of loss of turgor as water is available. Stomata are open all the time and on the upper surface of the cell so they are in contact with the cells. Reduced structure to the plant= the water supports the leaves and the flowers so there’s no need for supporting structures Wide flat leaves Small roots= water can diffuse directly into the stem and leaf tissues so there is less need for uptake by root Large surface area of stems and roots under water= Maximises the area for photosynthesis and for oxygen to diffuse into submerged plants Air sacs to enable the leaves and flowers to float on the surface of water. Xerophytes Cacti= Have: Tap roots - these are long roots that reach deep under the ground to access water supplies. Spines - some plants have spines instead of leaves eg cacti. Spines lose less water than leaves so are very efficient in a hot climate. Spines also prevent animals from eating the plant. Waxy skin - some leaves have a thick, waxy skin on their surface. This reduces water loss by transpiration. Water storage - some plants, known as succulents, store water in their stems, leaves, roots or even fruits. Hydrophytes Water lilies Wide flat leaves that spread along the surface of the water to capture as much light as possible. Stomata on the upper surface of the leaf so they are in contact with air. Marram grass Bibliography Ann Fullick, P. B. (2015). oxford university press. Retrieved 05 07, 2021, from kerboodle: https://www.kerboodle.com/api/courses/18594/interactives/113873.html Desertification. (n.d.). Retrieved 05 07, 2021, from BBC bitesize: https://www.bbc.co.uk/bitesize/guides/zctymnb/revision/2 Dominic Corsini. (n.d.). Xerophytes: Definition, Adaptation & Examples. Retrieved 05 06, 2021, from Study.com: https://study.com/academy/lesson/xerophytes-definition-adaptationexamples.html . .
