DIRECTIONS FOR THE TREE LEAF COLLECTION & KEY EXERCISE
Objectives of the exercise:
1. Students should display the ability to identify leaves using a dichotomous key.
2. Students should verify the accuracy of their results by consulting with another leaf/tree identification reference.
3. Students should understand the basic methodology of creating a scientific collection.
Collect 5 leaves (FROM TREES) and identify their GENUS (or a closely related Genus) using a dichotomous key on the web for this exercise. This collection will be worth 40 points making each leaf worth 8 points. You will be graded on the presentation of your leaves as well as an outline of your use of a dichotomous key to identify a Genus for each leaf. All tree Genuses may not be identified by the key you use so the key may tell you the leaf is from a Genus you know is incorrect. THAT’S OK, the point is - you are to demonstrate your ability to use a dichotomous key to arrive at an identification of the leaves.
Dichotomous keys to use (be sure you reference which key you use in your collection):
You should be able to identify your leaves with one of the following keys. Note these are both supported by Virginia schools so hopefully the trees identified in them are similar to what we’d find here in East Tennessee.
Virginia Tech’s key at http://www.cnr.vt.edu/dendro/dendrology/syllabus/key/location.htm
You should click on the description not the picture of the leaves to work you way through the key.
Blue Ridge CC’s key at http://www1.brcc.edu/murray/Interactive_Key/index.html
You should click on the numbers and letters to work your way through the key.
Check for an email containing links to the keys which will allow you to just click on them to follow.
Once you have identified a Genus for each leaf with a dichotomous key, consult a tree/leaf identification book and verify that the dichotomous key guided you to the correct Genus. If the dichotomous key was inaccurate, indicate the correct Genus provided by the leaf identification book you consult. There will be some leaf identification books on reserve at the library of each campus. Leaf identification books should also be available at the public libraries.
1. A pinnately or palmately compound leaf (attached to a very small piece of branch). To help you correctly identify a simple vs. a compound leaf, look for the axillary buds. Each LEAF will have an axillary bud associated with it, but leaflets will not.
2. Simple leaves with alternate pattern of attachment. (2 leaves attached to branch)
3. Simple leaves with opposite pattern of attachment. (2 leaves attached to branch)
4. A simple leaf with a toothed or lobed margin. This can be from the same Genus of trees as your simple with attachments, but MUST be from a different species.
5. Some type of needle-like leaves from a cone producer.
You will need to collect at least two leaves that are attached to a branch to illustrate your successful collection of simple leaves with alternate or opposite attachment. You need to collect an entire compound leaf, not just a leaflet, which is attached to a small section of the branch so that opposite or alternate attachment of the leaves is clear. Your collection should include the five required leaves period, “spares” will not be accepted/considered during the grading process.
Extra Credit - you may earn up to five points of extra credit on this assignment.
Items worth extra credit: descriptions of the trees identified; samples of flowers, fruits, cones, tiny bark pieces; art work, table of contents (that lists the order of the 5 required leaves), word processed labels.
Presentation of your leaves:
1. You should PRESS your leaves. You can do this by placing the leaf between 2 paper towels or 2 pieces of newspaper and inserting it into a thick textbook/encyclopedia/dictionary. It takes about a week for the leaves to dry sufficiently.
2. You should SEAL your leaves in plastic. Leaves may be inserted into plastic sleeves (designed to go into notebooks) or may be covered by clear contact paper.
3. You should LABEL your leaves. Your leaves should be labeled with:
a. which of the five required leaves is represented.
b. the Genus, as identified by the key, of the trees from which you collected the leave.
c. the specific place or area where you collected your leaves (for example - PSTCC main campus; Tyson Park, Knoxville, TN; 102 Kingston Pike, Knoxville, TN). The idea is anyone should be able to locate the trees from which you collected your leaves. “Behind granny’s house” is not specific enough and the date on which you collected your leaves.
d. a step-by-step explanation of how you used the dichotomous key to identify the Genus of your leaves (trees) AND a reference for the key you used!
e. verification of the results of the key and a reference for the leaf identification guide you consulted; include the page number from the reference for each verification.
f. your lecture instructor’s name
There should be a sample leaf collection in each lab that you can look at to see what a good/bad leaf collection looks like. There should be comments included with the samples so you’ll know what the instructors will be looking for.
Here’s an example of what you should do:
Simple leaves with opposite attachment.
Web key used http://www.cnr.vt.edu/dendro/dendrology/idit.htm
Leafy broad leaves
Opposite leaf arrangement
Genus - Acer
Collected 4-14-09 from One Oak Farm; 234 Jones Rd.; Anytown, TN.
Verification: Leaves correctly identified as Genus Acer. Source: Brockman, C. Frank. Trees of North America. Golden Press. 1986. p. 210.
Dr. Anderson = lecture instructor