Seed Plants: Gymnosperms

Concepts to Be Covered

• A seed contains an embryo, a food supply, and a protective seed coat. Seed plants are classified into two classes depending on whether or not their seeds have coverings.
• Gymnosperms are vascular plants that develop uncovered seeds. The main group of gymnosperms is the conifer. Conifers produce seeds in cones. Conifers are major lumber and paper producers.

Goals for the Lesson

Students will be able to:

• identify what makes up a seed.
• explain what gymnosperms are and describe some places where they are found.
• identify conifers and explain how they reproduce.
• discuss the importance of gymnosperms.

Introduction

Have students name 10 plants with which they are familiar. If they have difficulty, suggest fruits, vegetables, trees, or plants that grow in their neighborhood. Tabulate the lists and indicate the number of times certain plants are suggested. Most of the plants they list will probably be seed plants. Have students try to classify the plants into two groups based on type of seed and discuss the results.

Procedure

1. Introduce the words gymnosperm, which means "naked seed" and angiosperm, which means "covered seed." Show examples of each type.
2. Cut an angiosperm seed in half and point out the embryo, food supply, and protective coat. The food supply surrounding the gymnosperm embryo should not be confused with the fruit of an angiosperm. Show the students examples of gymnosperm cones and angiosperm fruits and point out the differences.
3. Discuss the four orders of gymnosperms: the cycads, the gingkoes, the gnetales, and the conifers. On a world map, show where these gymnosperms are found. Note that many species of gymnosperms may have become extinct, since they may not have been able to adapt to the colder climate of the glacial periods.
4. Introduce the term conifer. Ask the students to name the different kinds of conifers. Point out that conifers hold some of the records for size and age. If any students have seen sequoias, redwoods, or bristlecone pines, ask the students to share their experience and any pictures that they might have.
5. Show students a variety of conifer leaves and have them note the common characteristics. On a world map, show the students where conifer forests are located.
6. Point out that the size and shape of the needles and cones are used to classify conifers. Show examples of needles and cones and have students identify the conifer.
7. Discuss the life cycle of the conifers. Show examples of both the male and female cones. Examine pollen using hand lenses or microscopes.
8. Discuss the importance of conifer products: lumber, paper, and other forestry products. Discuss the role of the conifers (food, protection, shelter) in forests as part of the community and food web.

Evaluation

Ask the students the following questions and discuss:

1. What are the three parts of a seed?
2. What are gymnosperms?
3. What is the largest group of gymnosperms?
4. How do conifers reproduce?
5. How are conifers important?

Reinforcement

Divide the class into groups of four. Assign each group a conifer to study. Each group is to gather information about the conifer's appearance, importance, distribution, and uses. The groups should compile the information for a 5-minute TV news report. Pictures, drawings, or specimens should be included.

Reference

Bierer, Loretta (1984). Heath Life Science. Lexington, Mass.: D.C. Heath and Co.

Author

Rosemary Grove, Cathedral Center