Plant Structure and Function

INTRODUCTION

Plants are living things that make their own food using energy from the sun. There are thousands of different plants on earth, some living on land and others in water. Each type of plant has different structural features to help it survive. The most common type of plant is the flowering plant; they are all made up of roots, stems, leaves and flowers. Investigating the structure of flowering plants will provide a better understanding of how the plant lives and functions.

MATERIALS

WHAT TO DO

  1. Use the large, hands-on model to learn the parts of the flower.
  2. Then, with the knowledge gained from the model begin working with the live samples by identifying the parts of the flowering plant. The roots grow in the ground, collect water and nutrients from the soil, and anchor the plant in the ground. Use the magnifying glass to closely observe the many tiny, water-absorbing hairs on the roots.
  3. The stem grows above the ground and connects the roots to the rest of the plant. Transport of water, food and nutrients takes place in the stem and the stem supports the leaves and flowers. Carefully cut the stem and use the magnifying glass to observe the tubes that carry water and food inside the stem.
  4. Leaves grow from the stem(s) of the plant and can have many different shapes and sizes. The transformation of the sun’s energy into food takes place in the leaves, so all true plants have leaves. Leaves are also important in regulation of water. Transpiration, or release of water, takes place in the leaves so that the roots can draw in fresh water. Use the magnifying glass to carefully look at the leaves and their veins.
  5. Flowers are responsible for reproduction, production of seeds that can grow into new plants. The many parts of the flower are designed for reproduction. Flowers begin as buds, with sepals surrounding them for protection. The sepals are forced apart to reveal the petals as the flower starts to bloom. The petals surround the pistil and the stamens. In the center of the flower is the pistil and stamens surround the pistil. Each stamen has a stalk, called the filament, that holds up the anther where pollen is produced. When the pollen is ripe it is released from the anther into the air so it can come into contact with the pistil, fertilize the ovules contained in the pistil, and form seeds. Identify all parts of the flower on the live sample.
  6. Look at different flower samples and try to identify all the parts of the flower.

QUESTIONS

  1. What are the main parts of flowering plants? What does each of those parts do to help the plant live?
  2. What two parts of the flower are responsible for reproduction?

SUMMARY

Roots, which are most often found in the ground, are important for plants’ water uptake and nutrient storage. Roots also help stabilize the plant as they hold it firmly in the ground. Carrots and radishes are examples of roots that we eat. The stem of a plant transports water from the roots to the leaves so that the plant can grow, the leaves can develop, and sunlight can be found for the formation of food through photosynthesis. Leaves grow from the stem of the plant and can have many different shapes and sizes. The transformation of the sun’s energy into food, photosynthesis, takes place in the leaves, so all true plants have leaves. Leaves are also important in regulation of water. Transpiration, or release of water, takes place in the leaves so that the roots can draw in fresh water. There are two types of leaves, simple and compound; simple leaves are those with only one leaf blade on a stalk while compound leaves are those with more than one leaf blade on a single stalk.
Flowers are responsible for reproduction, production of seeds that can grow into new plants. The many parts of the flower are designed for reproduction. Flowers begin as buds, with sepals surrounding them for protection. The sepals are forced apart to reveal the petals as the flower starts to bloom. The petals surround the pistol and stamen of the flower that interact for reproduction. In the center of the flower is the pistil, the female part that contains the ovary, which houses the egg cells, called ovules. Stamens, the male parts of the flower, surround the pistil. Each stamen has a stalk, called the filament, that holds up the anther where pollen is produced. When the pollen is ripe it is released from the anther into the air so it can come into contact with the pistil. The pollen fertilizes the ovules in the ovary and seeds begin to form. Flowers’ beautiful petals are designed to attract pollinators, such as bees and butterflies. Some petals even have markings that point in the direction of the nectar the bees have come to collect.

SOURCES

"Exploring Plants." Ed Catherall, Steck-Vaughn Company: Austin, Texas, 1992. ISBN 0-8114-2601-7
"Plant Life." Peter Riley, Groiler Publishing: New York, 1998. ISBN 0-531-14507-7

© S. Olesik, WOW Project, Ohio State University, 2003.

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