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HorseCrazy93 (31/2347)

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Plant Survey: Native and Exotic Plants

Summary | Level | Objectives | Sources | Estimated Time to Complete | Materials Needed | Procedure | Classroom Assessment | Extensions/Adaptations | Relevant National Science Education Standards

For easier printing, download this lesson plan as an Adobe PDF (141K).

Summary: Your own backyard contains many varieties of plants, each with their own story to tell: some are ancient residents of your state whose ancestors evolved there; others are immigrants with a more recent past history of living in this habitat. The old-timers are called native species; the newer arrivals are called exotics or non-native, alien species. It is often difficult to tell them apart, because there are successful populations of both in most places, but reference books and plant-identification guides specific to your state can tell you which of the plants living in your backyard are natives or exotics. Some of the beautiful plants we love are exotics in America, like English ivy, Chinese wisteria or Japanese honeysuckle; others are considered undesirable weeds, like wild onion, common cockleburr, Japanese stiltgrass, kudzu or chickweed.

Frequently, exotic plants become weedy invaders because their natural predators are missing in their new home. For example, in 1788 a prickly pear cactus was planted in Australia for use as an exotic hedge plant. By 1910, ten million acres were invaded by the thorny plant, which had no natural enemies in their new country. The cacti were brought under control by introducing the eggs of a brown moth whose larvae burrow into the cacti roots and stems. Introducing exotic plants into your backyard can have destructive consequences! Of the 4,000 alien plant species introduced into the U.S. that have escaped our plans to cultivate them, about 400 are serious pests that now infest over 100 million acres. Native plant species are generally considered more desirable for the ecosystem because they have ties to the whole food web. They provide food for, and are better dispersed by, native animals, are pollinated by native insects, and are better adapted to the soils and weather of their home habitat.

This lesson will introduce students to the concept of native and exotic plant species through outdoor observations, classroom discussions, online activities and the use of reference materials. Students in grades 5-8 will survey the plants in their backyards, compare and contrast their backyard discoveries with classmates, and share their findings with others via the Backyard Jungle Web site. Each state has its own native plant society to help you identify the native and exotic plant species in your area. Links to these resources can be easily found by typing "native plant societies" into your online search engine.

Objectives: Students will be able to:

• Identify 10 plants in their backyard to categorize as either native or exotic
• Record the relevant characteristics of each plant using the downloadable form enclosed
• Define what is meant by native vs. exotic plant species
• Discuss the relative merits of native plant species and the possible ecological dangers associated with introducing exotic plant species
• Write about how plant populations are kept in balance by being part of a larger food web

Sources:

• Vessel, Matthew and Herbert Wong, Natural History of Vacant Lots, California History Guide No. 50, University of California Press, Berkeley, 1987
• Native Plant Societies Web sites
• Visit the New England Wild Flower Society Web site for a listing of native plant societies in the United States and Canada. Go to www.newfs.org/nps.htm.

Estimated Time to Complete: 3 to 4 hours (minimum: 1 hour classroom discussion, 1 hour computer lab, 1 hour outside)

Materials Needed:

• Rulers
• Downloaded form available on the Backyard Jungle Web site Download this worksheet as a PDF (100K)
• Digital cameras (optional)
• Pencils
• Reference materials and plant identification guides specific to your state. Keep in mind, each state has its own native plant society to help you identify the native and exotic plant species in your area. Links to these resources can be easily found by typing "native plant societies" into your online search engine.

Procedure:

1. Introduce to the class the difference between native and exotic species. Provide examples.
2. Tell why these plants are difficult to distinguish based upon their characteristics alone. Thriving populations of both native and exotic species should be readily available in all schoolyard areas.
3. Explain to students the harm that can potentially come to a habitat when a new plant species is introduced into it. Provide examples.
4. Pass out rulers, pencils, downloaded forms and digital cameras (if available). Download this worksheet as a PDF (100K)
5. Lead students outside and encourage them to discover 10 different plant species to identify and draw/photograph.
6. Assist students in identifying and recording the information requested about each plant. Students should fill in the downloaded form with as many examples as possible. Use additional reference materials as needed to correctly identify the Discoveries.
7. Direct the students indoors. Students may need additional time to research their Discoveries and appropriately identify them as native or exotic species.
8. Facilitate discussions among students about their Discoveries. Divide students into small groups to compare/contrast their findings. Students may share their drawings and photographs. What kinds of native species were identified? What exotic species were discovered? How are the subjects drawn/photographed by other students similar or different? Ask students to explain and provide examples to support their observations.
9. Follow the small group discussions with a larger class discussion. What varieties of exotic vs. native specifies did the class discover? What noticeable impact do the exotic plants have on the surrounding environment? What theories do students have about where the exotic plants came from? If applicable, how have their Discoveries changed over time (minutes, days, weeks, seasons)?
10. Direct the students to the computer lab and have them go to the Backyard Jungle Web site: pbskids.org/backyardjungle/. Have students create member Ids/passwords and share their findings online by creating new Discoveries and/or Backyards with other Backyard Jungle members. Students should be sure to categorize their Discoveries as "native" or "exotic" when submitting them online. Visit pbskids.org/backyardjungle/info/wheredoistart.php for more information.
11. Repeat the above sequence of events on a regular basis to see how their own Discoveries and Backyards (and those of other Backyard Jungle members) change and develop over time.

Classroom Assessment: Using the rubric below, evaluate each student's understanding of the concepts presented.

Extensions/Adaptations: To adapt the Plant Survey: Natives vs. Exotics lesson plan for younger children (grades K-4th grade), the teacher should prepare specimens from the school yard of both native and exotic plant species (10 plant examples total). The teacher should lead the class to each population of plant while outdoors and allow students to finish the downloadable worksheet under the teacher's supervision.

Relevant National Science Education Standards:

Science as Inquiry: Demonstrates abilities necessary to do scientific inquiry
• Use appropriate tools and techniques to gather, analyze, and interpret data
• Think critically and logically to make the relationships between evidence and explanations.

Life Science: Understands the characteristics of populations and ecosystems
• A population consists of all individuals of a species that occur together at a given place and time. All populations living together and the physical factors with which they interact compose an ecosystem.

Life Science: Understands diversity and adaptations of organisms
• Biological evolution accounts for the diversity of species developed through gradual processes over many generations. Species acquire many of their unique characteristics through biological adaptation, which involves the selection of naturally occurring variations in populations. Biological adaptations include changes in structures, behaviors, or physiology that enhance survival and reproductive success in a particular environment.
• Extinction of a species occurs when the environment changes and the adaptive characteristics of a species are insufficient to allow its survival. Fossils indicate that many organisms that lived long ago are extinct. Extinction of species is common; most of the species that have lived on the earth no longer exist.