Structure and Function In Different Environments Introduction Plants have various structures that help them to survive in different environments. In this presentation, we will look at the adaptations in the structures of plants, including roots, stems, and leaves of plants in different environments. We will compare the structure and function of plant parts from the following environments: desert, wetlands, forest, and tundra. Desert- A Definition A desert is a region that receives an extremely low amount of precipitation (rain or snow), less than enough to support growth of most plants. Plants lose a lot of moisture through a process called transpiration. (Sort of like a person losing water through perspiration.) Deserts can be hot or cold. Wetlands- A Definition A wetland is an area between a land-based and a water-based ecosystem. Wetlands include bogs, fens, marshes, and swamps. Although there are many different types of wetlands, they have three physical characteristics in common. Wetlands- A Definition Water – Wetlands are covered with shallow water for at least some time during the year. Soil – The soil often has little or no oxygen. Plants – Wetlands provide habitat for “water- loving” aquatic plants (hydrophytes). These plants are adapted to living in saturated (really full of water) soil all or part of the year. Tundra- A Definition The word "tundra" usually refers only to the areas where the subsoil is frozen all the time (permafrost). The plants in this environment include shrubs, sedges, grasses, mosses, and lichens. Forest- A Definition A forest, or woods, has many trees. There will usually be an upper tree layer (canopy) and the understory. Other plants, such as shrubs, vines, flowers, and mosses, are found in forests. Forests can include rainforests, boreal forests, and conifer forests. Roots The four major functions of roots are: Absorption of water and nutrients (food) Anchoring the plant to the ground Storage of food and nutrients To prevent soil erosion Buttress roots are large roots on all sides of a tree with a wide base or a tree with shallow roots. Roots: Dry Environment Some desert plants have long taproots that go all the way to the water table, if present. Some desert plants have adapted to the weather by having widespreading roots, to absorb water from a greater area of the ground. Roots: Wetland Environment Emergent – Rooted in soil, but plant parts extend above the water Submergent – The entire plant lives underwater. Roots: Wetland Environment Floating – Leaves float on the surface, while roots hang down into the water or are planted in the soil Riparian – Found along the edges of wetlands or other water bodies Roots: Tundra Environment There are no deep root systems in the plants (vegetation) of the arctic tundra. Many plants have rootlets (rhizoids) instead of roots. Stems A stem is the part of the plant that usually grows above the ground and holds the leaves. The stem has four main functions: Supports and elevates the plant, leaves, flowers, and fruits Transports fluids between the roots and the shoots Stores nutrients Produces new living tissue Stems Some plants have thorns on their stems for protection. Some plants have stems that wrap around other plants or structures. This provides a way to support the plant as it grows. Stems The stems of many desert plants feel “waxy”. Some desert plants store water in their leaves, roots, and stems. The stems of tundra plants are often very short. Plants grow close to the ground in this environment. Tundra plants do not have woody stems. Stems The stems of many aquatic plants are flexible. Flexible stems move easily in water currents. Leaves The shape and structure of leaves varies considerably from plant to plant. The main purpose of leaves is to produce food (energy). Another purpose of a leaf is to get carbon dioxide from the air (atmosphere) to make sugar and release oxygen. Leaves: Dry Environment (desert) Desert plants often have small, spiny leaves. They are designed to reduce water loss in the plant. Leaves: Temperate Environment (forest) Some trees have broad leaves that absorb water and sunlight. Some trees have “needles” for leaves. The needles’ shape and waxy coating help the plant conserve water during the cold winter and in hot climates. Leaves: Tundra Environment Tundra plants have very tiny leaves. There are usually many leaves on one stem. Sometimes the leaves appear to be “wooly”. Leaves: Wetland Environment Leaves are usually round and flat or long and thin. The flat leaves float on the surface. The thin leaves move easily when water flows. Special Structures… Carnivorous plants have adapted to living in the lownutrient areas of wetlands (bogs and fens) in a special way. They have structures that allow the plant to trap and digest insects. The insects provide the necessary nutrients that they cannot obtain from the soil.