Exercise 1: Plant Identification







For many people, one of the more enjoyable aspects of knowing something about biology is being able to teach others about the things they encounter on walks and hikes. Whether its stroll through a local park or a backpacking trip in the High Sierras, the ability to relate what you've learned in the classroom to real life is exciting. Being able to identify the living organisms can be particularly enjoyable and turns into a life long hobby for those interested in studying birds, wildflowers, trees, etc.


Since the animals tend to run away from humans whenever possible, it is frequently the plants surrounding us that are most available for identification. While it is not possible to teach you to identify the thousands of types of plants out there, it is possible to introduce you to the basic techniques used in identifying organisms and then to give you practice using these techniques on some common Southern California plants. Any future endeavors you should make into this area of science should be assisted by the use of an identification book for the area and type of organisms you are interested in. Books are readily available at libraries and bookstores to identify your area's birds, rocks, wildflowers, mushrooms, trees and just about any thing you are interested in.


While their format will differ, they will usually start you off with a very basic dichotomous key that is designed to help you narrow down your choices until you have identified the specific organism you are looking at. Such keys are basically like a pathway where, at each intersection you are asked a question. On the basis of your answer to that question you take either the right or left fork. As you continue on the path, you will come to other forks in the road with other, more specific questions that lead you closer and closer to your target. Imagine a trip you wish to make from Northern Nevada to APU. Your first decision would be when you enter the 5 freeway and may ask if you want to go to Northern California or Southern California. As you move along the 5 to Southern California you might come to a fork that asks if you wish to go to the Los Angeles area on the 210 freeway or continue on to the San Diego area. After traveling on the 210, the next decision point would be whether to go south on the 605 or continue on the 210. At the Citrus exit you have the choice of continuing on the 210 to Glendora or getting off for Azusa. At Citrus you have to decide whether you want to go right towards Covina or left towards Azusa. Finally, at the Alosta Avenue intersection you have to decide which way to go until you finally get on our campus. You have just used a dichotomous key to "identify" your desired location.


Keys used to identify plants work this way based upon the size of the plant, nature of the leaves, types of flowers, smell of the bark, etc. The simplified key we will work with here will be of use in identifying some of the plants in the Interpretive Garden. It will not identify all plants in the garden so be sure and stick with those plants assigned by the professor. You will be able to verify your identification for most of these plants by using the website located at:


Once at this site, select the "Garden Maps" option and click on the portion of the garden your plant is located in. When you click on the actual plant icon representing your chosen plant the plant's scientific and common name will be shown. The identification of the ones not on this list will be provided by your professor.





Materials Needed:

Dichotomous Key for the Interpretive Garden

Interpretive Garden Map with marked plants

Internet connection to:

Assorted sizes of beakers (at least three)

Assorted glass marbles (at least three)

Assorted Styrofoam balls (at least three)

Assorted small rubber balls (at least three)




1. Select five of the plants marked on the Interpretive Garden Map provided and locate them one by one. In the "Results" section, record the letter designation for the selected trees in each space provided.

2. Using the Dichotomous Key for the Interpretive Garden, identify each of the five plants suggested recording the "path" followed from the Dichotomous Key.

3. Use the Internet connection to the Garden Map to verify the identification for each plant. Simply select the quadrant of the garden that each plant is in and click on it to go to a more detailed map. Click on the plant you are attempting to identify and record the name given.

4. Compare your results with the correct answers.

5. Create a dichotomous key for the objects provided by your professor. Have a member of your groups use your key to identify the objects.




1. Complete the following for each plant selected for identification:

First Plant

# of

Choice Description of


Your ID:

Map's ID:


Second Plant

# of

Choice Description of


Your ID:

Map's ID:


Third Plant

# of

Choice Description of


Your ID:

Map's ID:






Fourth Plant

# of

Choice Description of


Your ID:

Maps ID:


Fifth Plant

# of

Choice Description of


Your ID:

Map's ID:



Number correctly identified:

Number incorrectly identified:


2. Dichotomous Key for Miscellaneous Objects:

























1. For any plant incorrectly identified the first time, trace backwards on the key from the correct name and determine where your mistakes occurred. Explain what led you to your incorrect conclusion.

2. What was the most difficult part of creating your own dichotomous key?



3. Did your key allow your colleague to identify the objects?






1. Leaves as:

a. needles 2

b. not needles 5

2. Needle length:

a. under 2" long 3

b. over 2" long Torrey Pine


3. Needle arrangement on branch:

a. flat 4

b. whorled Deodar Cedar


4. Color of needles:

a. green all over Red Cedar

b. white underneath Sequoia


5. Venation pattern:

a. parallel 6

b. net 7


6. Plant size:

a. small Lily

b. large Lord's Candle


7. Stem pattern:

a. single trunk, tree-like 8

b. multiple trunks, bush-like 10


8. Leaf margin:

a. serrate Summer Holly

b. lobed California Black Oak

c. entire Redbud

d. cleft 9


9. Leaf size:

a. less than 2" Scrub Oak

b. greater than 2" Liquidamber


10. Leaf size:

a. less than 2" Sage

b. greater than 2" Manzanita