1. Baker County Arboretum Tree Identification Techniques
Florida is home to many tree species, with both Florida native and Florida-Friendly (non-invasive) trees found readily in forests and landscapes throughout the state. The Baker County Arboretum is home for 35 different species of trees, many of which are underutilized in landscapes. But how does one tell them apart?
Trees do share similar characteristics, but there is at least one characteristic that sets them apart from others. This is how we identify trees and all it takes is a little knowledge and the right tools to be successful at positively identifying one tree from another.
Alicia Lamborn, Horticulture Agent
UF/IFAS Extension Baker County

2. Baker County Arboretum Tree Identification Guide
The Baker County Arboretum is home to 35 different Florida native and Florida-Friendly tree species and cultivars. But how does one go about telling them apart?
To identify the trees successfully, follow these steps:
Learn to recognize leaf arrangement (alternate vs. opposite).
Learn to recognize leaf divisions (simple vs. compound leaves), including even-pinnately compound and odd-pinnately compounds leaves.
Review the diagrams illustrating selected leaf shapes.
Review the diagrams illustrating selected leaf margins.
Follow the tree identification guide (also known as a dichotomous key).
Today, we’re going to give you those tools to help you become a tree ID expert. Each participant should have received a tree ID guide which teaches you the basic steps we’ll use to identify the arboretum trees (and other plants). After we’ve gone through the steps and everyone feels comfortable, we’ll out to the arboretum and complete a tree ID activity to apply our new knowledge and practice our skills.
To identify the trees in the arboretum successfully, one must familiarize themselves with select plant identification terminology, including leaf arrangements, leaf divisions, leaf shapes and leaf margins. Once reviewing these terms, we’ll then discuss how to read and use the tree identification guide, also known as a dichotomous key.
There are, of course, many more plant identification terms used to identify trees and other plants than the ones we will learn today. However, the plant identification terms presented in this guide are those needed to identify the trees in the Baker County Arboretum, which is a good start!

3. Step 1: Leaf Arrangement
How leaves are arranged on the stem.
Alternate: Leaves borne singly at each node (the position on the stem where leaves or branches originate), alternating sides of the stem.
Since this activity was designed as an inductive learning experience, the instructor should ask for a volunteer to read the definitions of each plant identification term. Afterwards, have a volunteer explain these differences in their own words. The instructor should provide support and feedback when students get stuck. Remember to ask if there are any questions before moving on.
Opposite: Leaves borne across from one another at the same node (the position on the stem where leaves or branches originate).

4. Step 2: Leaf Divisions SIMPLE EVEN-PINNATELY COMPOUND COMPOUND
Step 2 is to identify the leaf division, or how leaves are divided on the plant. A simple leaf, is simply a single leaf arising from a bud (node) on the stem. A compound leaf also arises from a bud (node) on the stem, but is separated into two or more distinct leaflets. The way to tell the difference is to identify the placement of the bud. There is no bud located at the base of each leaflet, only at the base of each leaf (indicating that it is a compound leaf).
Compound leaves can be divided into two categories: Even-pinnately compound (having an even number of leaflets) and Odd pinnately compound (having an odd number of leaflets).
The instructor should ask the students additional questions to facilitate their understanding of the concept.
Example Questions To Ask Participants:
Do even-pinnately compound leaves always have six leaflets as shown in the illustration?
(No, they may have any number of leaves, as long as there is an even number.)
If there is a bud at the base of a single leaf, is it a simple leaf or a compound leaf? (simple)
If there is not a bud at the base of a single leaf, then we call it a _________ (leaflet), which indicates the leaf is ________ (compound).
ODD-PINNATELY COMPOUND

5. Step 3: Leaf Shapes Acerose: Needle-shaped
Step 3 is to learn leaf shapes. There are many different leaf shapes found on plants and trees, however today we will only learn three!
Why you ask? There are two main reasons. First, many tree species have the leaf shapes that are similar (hard to distinguish) and some even have a combination of leaf shapes. For example, a leaf could be described as ovate-elliptical, meaning egg-shaped but also elliptic, meaning narrowly oval. See how this could be confusing? By learning only three leaf shapes, we hope to aid in comprehension and reduce confusion when using the tree identification guide. The second reason we’re learning only three leaf shapes is because leaf margins can be used to distinguish between trees having the same or very similar leaf shapes, reducing the number of steps taken while following the tree identification guide.
Have a student read the definitions of the three leaf shapes and describe the differences in their own words.
Ask the group: Does anyone know what types of plants have these leaf shapes? If not, we will learn today!
Acerose: Needle-shaped
Awl-shaped: Scale- like; short, narrowly triangular, and sharply pointed like an awl.
Cordate: Heart- shaped, with the notch at the base.

6. Step 4: Leaf Margins
Lobed: Bearing lobes which are cut less than half way to the base or mid-vein.
Cleft: Leaf margin is cut or split about half- way to the mid-vein or base.
Entire: Margin is continuous, not toothed, notched, or divided.
Step 4 is to learn leaf shapes.
Have students read aloud the definitions of each leaf margin. As a group, have the students come up with an alternative name that they feel describes the margin. This should help them to remember the name once they see it in the plant identification guide. If they have trouble, use the examples below or use your own examples to assist them.
Examples:
Entire – smooth
Lobed – ear lobe
Cleft – deeply lobed
Crenate – bumpy
Serrate – Serrated knife
Serrulate – small teeth
Serrulate: Toothed along the margin, with minute, sharp, teeth (double serrate).
Serrate: Toothed along the margin, the sharp teeth pointing forward.
Crenate: with rounded teeth along the margin.

7. Step 5: Follow the tree ID guide (dichotomous key)
A dichotomous key is a tool that allows the user to determine the identity of items in the natural world, such as trees. Keys consist of a series of choices that lead the user to the correct name of a given item.
To use the key, start by determining which number category the tree fits into (listed 1, 2, 3, 4, or 5). Then (within the numbered category) determine which subcategory the tree fits into (listed i, ii, iii, iv, etc.), and so on. By eliminating certain characteristics, the user should be led to the correct name of the tree in question.
Step 5 is to learn about dichotomous keys and how they are used to identify not only trees, but all items in the natural world.
Ask a student to read the definition and instructions for using the dichotomous key. Using the key provided, ask students to follow along while the instructor provides an example (next slide).

8. Using the dichotomous key
Baker County Arboretum Dichotomous Key:
1. Trees with acerose (needle-like) or awl-shaped (scale-like) leaves
i. Needles held in bundles
a. 2 needles per bundle…Spruce Pine (Pinus glabra)
b. 3 needles per bundle………Longleaf Pine (Pinus palustris)
ii. Scales: tiny, overlapping Southern Red Cedar
(Juniperus virginiana var. silicicola)
The instructor should allow students to practice using the dichotomous key, by providing an example. Start by providing examples without the actual tree in front of the group.
Example 1: This tree has needle-like leaves held in bundles of 3. What type of tree is it?
This will allow the students to practice finding the right category and narrowing down to the correct subcategory.
That was an easy example, now let’s try a harder one…

9. Using the dichotomous key
Example 2: This tree has…
Alternate leaf arrangement
Simple leaf division
Cordate leaf shape
Serrate leaf margins
Allow the students to practice reading the dichotomous key using example #2. (Basswood)
If the students are having trouble reaching the correct answer, the instructor should go through the example step by step until everyone understands the process.

10. Using the dichotomous key
Example 3: This tree has…
Alternate leaf arrangement
Compound leaf division
Odd number of leaflets
Entire leaf margins
Undersides of leaves are pubescent (hairy)
Allow the students to practice reading the dichotomous key using example #3. (Mockernut Hickory)
If the students are still having trouble reaching the correct answer, the instructor should go through the example step by step until everyone understands the process.

11. Now Let’s Go Outside…
The next step is to go outside, choose two trees and practice individually identifying the trees using the key. Once everyone has an answer, discuss the steps as a group. This will allow the students to apply and reflect on what they have already learned from the illustrations alone. Once the students have had a chance to practice, let them complete the tree ID activity individually. After everyone finishes (or time has run out), go over the answers and collect the activity sheets for evaluation.