Section 1

Activity:
(Session 2): Using a Dichotomous Key

1.  Once students have learned the basics of how a dichotomous key is developed and used, they will then use the "Pacific Coast tree finder" and "Guide to native plants and noxious weeds of Monterey" to identify the 6  plants listed below (3 native and 3 non-native weeds). 
 
2.  Begin by defining a native plant. (ex.Native plants are plants that were present on the land before European settlers arrived on the North American continent.) Reinforce the fact that native plant communities of California have evolved over millions of years, with each plant fending off insects, animals, and diseases while competing with other plants for light, water, and nutrients. This slowly created a delicately balanced ecosystem. 

3. Now define an "invasive weed" as a plant species that infests large areas and causes economic or ecological damage to an area. Explain how these plants are introduced from another area. Explain that what one region calls a weed another region might call a native. Ask students to explain_____. 

4. Explain that weeds have left their native environment and have no competition from plant predators or other plants. Ask students: How might this throw off the "balance" of an ecosystem? 

5. Working in small groups or pairs, students should use the "RON Dichotomous Key"  to identify at least 6 plants, including 3 native and 3 non-native species. 

Note: The following plants are contained in the "RON Dichotomous Key". They are by no means, all of the common plants and weeds existing in Monterey. This guide was designed to give students a basic understanding of dichotomous keys. Educators may want to suggest plants that students should identify. (The educator should study the guide prior to this lesson.) For an additional reference in designing your own dichotomous key try using "An Illustrated Field Key to the Flowering Plants of Monterey County" by Mary Ann Matthews. 
 

Arundo 
Black Sage 
Bunchgrasses 
Cape Ivy 
Ceanothus 
Chamise 
Coast Live Oak 
Cobweb thistle 
Coyote Bush 
Dudleya 
French Broom 
Ice plant 
Lupine 
Shaggy Bark Manzanita 
"Hooker's" Manzanita 
Sandmat Manzanita 
Sticky Monkey Flower 
Pampas/Jubata Grass 
Poison Oak 
Yellowstar thistle 
Wild Cucumber 
 
 
 
 
 
 

Use the "Pacific Coast tree finder" to identify trees. Some common trees are: Monterey
Pine, Monterey Cypress, Coast live oak, California sycamore 
 

Wrap Up 

After students have identified the plants, have them choose a favorite species,
which they will research in greater depth. Students can use: "RON Plant Facts" or other books contained in the RON Toolbox. An excellent resource for plant information is the California Native Plant Societies website @  http://www.cnps.org/.

Teacher Help: Some suggested questions/discussion

Have students describe one of the unique qualities of the plant they identified? 
Have students describe the relation of plants to animals in ecosystem? 
Does it have any medicinal qualities? 
How did native inhabitants use it? 
Why it is weedy? 
Can students explain what makes a plant a "native"? 
Can students discuss what makes a plant a "weed"? 
Can students name and identify the noxious weeds mentioned? 

Journal (Options): 
Have students draw 2 noxious weeds and 2 native plants in their RON
journals. 
Have students write about their favorite plant. 
Have students write the answers to the questions above or form their own inquiry.