Effect of Environmental Moisture Levels on Stomata Density in Privet Hedges

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Introduction
Stomata are microscopic pores found on the epidermis of leaves. These allow material to pass in and out of the lead. The stomata are surrounded on both sides by guard cells. These guard cells control the opening and closing of the stomata by swelling or contracting. The guard cells close the stomata when dehydrated, allowing the plant to conserve water. Most stomata are found on the bottom surface of leaves. The number of stomata on a leaf’s surface can tell you a lot about the plant itself. Most often, a higher stomata density indicates a high amount of sun exposure and an abundance of moisture available to the roots. A lower stomata density indicates higher amounts of carbon dioxide. In other words, stomata density is determined by the conditions that the plant experiences while the leaf is developing.

During photosynthesis, stomata take in carbon dioxide (CO2) and release oxygen (O2) and some water (H2O) vapor. During respiration, the stomata take in O2 and release CO2 as well as some water vapor. During transpiration, a plant cools itself by opening its stomata and allowing water to evaporate. Energy needed to convert to convert liquid water to water vapor is drawn from the surrounding leaf surface, which is cooled in the process. Stomata are located on the lower surface of leaves to reduce water loss due to minimized solar radiation. The moist air in these spaces has a higher water potential than the outside air, and water tends to evaporate from the leaf surface. The stomata act as pumps that pull water and nutrients from the roots through the rest of the plant to the leaves in a phenomenon known as transpirational pull. Transpirational pull is one of the forces that drives water flow in the plant. Water is absorbed by the root hairs of a plant and, due to osmotic pressure, is passed through vascular tissues into the xylem where it is transported to the leaves and stomata. Vascular tissue is made up of more than one cell type and in plants...
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