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Objectives

Students should be able to:

  1. Review the origin and evolution of plants.
  2. Overview of the systematics or taxonomy of plants.
  3. Evolutionary trend in plants, and their evolution from aquatic to terrestrial habits
  4. Recognition and understanding of the major plant characteristics, reproduction and life cycles.
  5. Distinguish various plants features and specimens representing different plant groups.
  6. Appreciation of the role of plants as primary producers and source of economic benefits to man.
  7. Appreciate the roles of plants in ecological systems.

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Introduction

It is possible that the group of organisms that are referred to as plants today, may have had a few lines of evolutionary origin. Non-vascular plants, such as mosses and liverworts, that have remained “amphibious” probably evolved along a separate line from the larger, vascular, terrestrial groups that dominate the earth’s landscapes today. However, all plants may have evolved from plant-like protists, more specifically, the algae. There is evidence for this view, which is reviewed elsewhere. Both algae and plants share certain key characteristics, and both are eukaryotic, i.e., have membrane–bounded specialized cell compartments (organelles) in which various metabolic functions take place.

The early plants that colonized the terrestrial environment must have tackled formidable challenges in temperature and moisture fluctuations, the force of gravity, etc. Some of these (e.g., mosses and liverworts referred to above), have remained restricted to moist environments, and have not really evolved the structures that are vital for terrestrial challenges.

Plants are primarily terrestrial, multicellular eukaryotes that have well developed tissues, even though some of them lack vascular tissues for conducting water and organic materials. Plants have chlorophylls and other pigments that enable them to manufacture organic compounds in the process of photosynthesis. Their cells contain cell walls that are made of cellulose. Recall that the cell wall materials in bacteria and fungi are made of peptidoglycan and chitin, respectively.

Plants are broadly divided into vascular and non-vascular, and the latter into seedless vascular, and seed vascular plants. The seed plants, in turn, are divided into gymnosperms (non-flowering plants) and angiosperms or, flowering plants. Flowering plants may be either monocotyledonous or dicotyledonous, depending on whether they have single or paired seed leaves. Numerous other morphological and anatomical characteristics reflect these categories and sub-categories of plants.

In both terrestrial and aquatic environments, plants provide invaluable support to the ecosystems through primary production (synthesis of foods) and production of oxygen and shelter to countless animals. Plants provide us medicines, building materials in the form of wood, fibers for fabric and bags, and numerous other products. Thus, it is simply inconceivable to imagine life on earth without the vital roles played by plants

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Pre-lab Activities

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Pre-Lab Activity #1 - Life Cycles

Using resources available to you, find representative labeled imagery of the following:

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A typical moss life cycle

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A typical fern life cycle

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A typical flowering plant life cycle

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Pre-Lab Activity #2 - Imagery of typical nonvascular and vascular plants.

Using resources available to you, find representative labeled (if possible) imagery of the following:

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Typical moss plant (i.e. Polytrichum sp.)

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Marchantia sp.

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Lycopodium sp. (i.e. L. obscurum)

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Typical fern plant (i.e. Thelypteris, Osmunda, Pteridium, Asplenium)

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Labeled diagram of a typical monocot flower and plant

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Labeled diagram of a typical dicot flower and plant

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Gymnosperm strobili

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Pre-Lab Activity #3 - Plant Dissection

Dissection guide for a typical flowering plant.

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Pre-Lab Activity #4- Data Collection Sheet

Download and print out the Data Collection Sheet for Plant Diversity

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Pre-lab Questions (html version)        Pre-Lab Questions (Word version)

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The Laboratory Activities and Data Collection

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Lab Activity #1 - Mosses

Materials:

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Specimen A - living moss plant

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Dissecting microscope

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Data Collection Sheet

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Moss Life Cycle Diagram

Procedures:

  1. Transfer specimen A, a living colony of moss, into an empty Petri dish.
     

  2. Observe its external anatomy under a dissecting microscope.
     

  3. Identify the gametophyte from the sporophyte parts. Sketch and distinguish the two.

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Lab Activity #2 - Liverworts (Marchantia sp.)

Materials:

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Specimen B  - Preserved sample of the liverwort, Marchantia

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Dissecting microscope

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Data Collection Sheet

Procedures:

  1. Examine under a dissection microscope.
     

  2. On the Data Collection Sheet, fill in the chart with the information requested. Indicate the generation of Marchantia you are viewing, and put a check mark and notes on any of the features noted.

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Lab Activity #3 - Seedless Vascular Plants

Materials:

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Specimen C - A seedless, vascular plant

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Dissecting microscope

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Data Collection Sheet

Procedures:

  1. Examine specimen C, a seedless, vascular plant.
     

  2. Answer the questions found on the Data Collection Sheet.

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Lab Activity #4 - Ferns

Materials:

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Specimen D - Fern (living and preserved)

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Preserved slide preparations of fern material

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Dissecting microscope

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Compound light microscope

Procedures:

  1. Examine specimen D, a fern, both living and preserved form.
     

  2. Examine the preserved slide preparations of fern reproductive structures from the sporophyte and gametophyte generations.
     

  3. Answer the questions on the Data Collection Sheet concerning ferns.

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Lab Activity #5 - Gymnosperms

Materials:

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Specimen E - Representative gymnosperm (branch with strobili)

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Dissecting microscope

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Data Collection Sheet

Procedures:

  1. Examine in detail, specimen E (leaves and strobili)
     

  2. Select various bundles of leaves and count the number of leaves in the bundle. Look for variations in numbers.
     

  3. Answer the questions on the Data Collection Sheet concerning gymnosperms.

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Lab Activity #6 - Angiosperms (Flowering plants)

Materials:

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Specimen of a representative flowering plant species

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Dissecting microscope

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Dissection guide for a typical flowering plant

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Data Collection Sheet

Procedures:

  1. Examine the representative flower, and using your dissection guide dissect the plant.
     

  2. Identify all of the flower parts, leaves, stem, and roots.
     

  3. In the space provided on the Data Collection Sheet, sketch the requested plant parts and label them.
     

  4. Answer the questions on the Data Collection Sheet.

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Post-lab Activity and Data Analysis

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Results and Analysis

  1. Fill in all data requested on the Data Collection Sheets.
     

  2. Answer all Post-Lab Questions.
     

  3. Attach all materials to the Data Collection Sheet or Post-Lab Questions as requested.
     

  4. Return all materials to the area designated by the instructor.
     

  5. Clean up your lab station.

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Post-Lab Questions (html version)    Post-Lab Questions (Word version)

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