Name: leaf traits and tree id with a key
Uploaded: 2023-04-30T06:37:07.000Z
Duration: 12 min 6 s
Channel: JoVE
Description: Leaf traits can help students identify trees with a dichotomous key. A dichotomous key is a nature ID tool that works by choosing between two characteristics at each step. The word dichotomous comes from two Greek words that mean "to divide into two parts."

K12 Standards

Alabama Course of Study Science

9-12

Environmental Science

Unity and Diversity

9-12.EVS.2.3.b

tree-identification-how-to-use-a-dichotomous-key

Tree Identification: How To Use a Dichotomous Key

1. Identification of a Set of 10 Unknown Samples
Use the dichotomous key (Table 1) to identify the 10 unknown leaf samples (Figures 6-15).
<ol>
	<li>Pick a leaf, and starting at number 1 on the key, answer each of the questions.</li>
	<li>Choose the statement that best describes the leaf in question.</li>
	<li>The column on the right lists either the tree species or a number that lists the next set of statements to consider. </li>
	<li>Continue until the key lists the name of the tree from which the leaf sample came, and fill in the blank table supplied (Table 2).</li>
</ol>
2. Field Investigation
Collect leaf samples from 5 trees, properly identify the trees using a field guide to trees, and record on a data sheet (Table 3).
<ol>
	<li>Select a tree to be identified.</li>
	<li>Collect one representative leaf sample from the tree. </li>
	<li>Glue it to a herbarium sheet with regular glue.</li>
	<li>Note whether the leaves have an alternate or opposite arrangement on the stems. </li>
	<li>Record this on the herbarium sheet and the data sheet.</li>
	<li>Measure the diameter at breast height (dbh) of the tree in inches.
	<ol>
		<li>This is done by measuring the circumference of the tree at 4½ feet above the existing grade. The diameter of the tree is calculated from the circumference using the formula d = C/Π. Record the circumference and the diameter on the data sheet.</li>
	</ol>
	</li>
	<li>Note on the data sheet what type of land use is nearest to the tree: single family residential, multi-family residential, small commercial business, industrial/large commercial business, or park/other vacant land.</li>
	<li>Repeat steps 2.1 – 2.7 for 4 additional trees. 5 total leaf samples should be collected.</li>
	<li>Using a field guide to trees of choice, identify the leaf samples.  Record the species on the data sheet.</li>
</ol>
3. National Tree Benefits Calculator
Using this software, the benefits of street-side trees can be calculated. This includes a tree’s annual benefits for storm water management, property value, energy efficiency, and carbon sequestration.
<ol>
	<li>Open up the iTree for education software tool found at http://www.treebenefits.com/calculator/ created by the USDA Forest Service, which means iTree tools are in the public domain.</li>
	<li>Using the National Tree Benefits Calculator (Figure 16) and the data collected on the trees, calculate the environmental benefit of each tree.  </li>
	<li>Record the results.</li>
</ol>
<img alt="Alternate leaf arrangement diagram, botanical study, leaf morphology analysis." src="/files/ftp_upload/10070/10070fig8.jpg" data-altupdatedat="1761830439000" data-alt="Figure 8">
<img alt="Alternate leaf arrangement diagram with single leaf specimen on white background." src="/files/ftp_upload/10070/10070fig9.jpg" data-altupdatedat="1761830439000" data-alt="Figure 9">
<img alt="Opposite leaf arrangement diagram; botany study aid displaying leaf pattern and structure." src="/files/ftp_upload/10070/10070fig10.jpg" data-altupdatedat="1761830439000" data-alt="Figure 10">
<img alt="Leaf morphology study, opposite leaf pattern, botanical specimen presentation." src="/files/ftp_upload/10070/10070fig11.jpg" data-altupdatedat="1761830439000" data-alt="Figure 11">
<img alt="Leaf morphology study, heart-shaped leaf on white, alternate venation, plant anatomy analysis." src="/files/ftp_upload/10070/10070fig12.jpg" data-altupdatedat="1761830439000" data-alt="Figure 12">
<img alt="Leaf morphology, alternate arrangement, plant biology study, botany, venation pattern analysis." src="/files/ftp_upload/10070/10070fig13.jpg" data-altupdatedat="1761830439000" data-alt="Figure 13">
<img alt="Alternate leaf arrangement, pressed specimen, botany study, plant morphology." src="/files/ftp_upload/10070/10070fig14.jpg" data-altupdatedat="1761830439000" data-alt="Figure 14">
<img alt="Botanical specimen, unknown plant species, herbarium sheet, taxonomy research." src="/files/ftp_upload/10070/10070fig15.jpg" data-altupdatedat="1761830439000" data-alt="Figure 15">
<img alt="Leaf morphology, diagram, displaying alternate arrangement on white background for botanical study." src="/files/ftp_upload/10070/10070fig16.jpg" data-altupdatedat="1761830439000" data-alt="Figure 16">
<img alt="Herbarium specimen analysis, plant sample on paper, botanical study, unknown species identification." src="/files/ftp_upload/10070/10070fig17.jpg" data-altupdatedat="1761830439000" data-alt="Figure 17">
Figures 6-15. Unknown leaf samples.
<img alt="National Tree Benefit Calculator webpage; input tree species, size, location for ecosystem benefits analysis." src="/files/ftp_upload/10070/10070fig18.jpg" data-altupdatedat="1761830439000" data-alt="Figure 18"> 
Figure 16. National Tree Benefit Calculator.
<table align="center" border="1" cellpadding="0" cellspacing="0" fo:keep-together.within-page="always">
	<tbody>
		<tr>
			<td>1</td>
			<td colspan="4">Is the leaf needlelike or scalelike? 
			Is the leaf a broadleaf?</td>
			<td>Row 2 
			Row 3</td>
		</tr>
		<tr>
			<td>2</td>
			<td colspan="4">Is the leaf scalelike? 
			Is the leaf needlelike?</td>
			<td>Red Cedar 
			Scotch Pine</td>
		</tr>
		<tr>
			<td>3</td>
			<td colspan="4">Is the leaf simple? 
			Is the leaf compound?</td>
			<td>Row 4 
			Row 5</td>
		</tr>
		<tr>
			<td>4</td>
			<td colspan="4">Is the leaf lobed? 
			Is the leaf unlobed?</td>
			<td>Row 6 
			Row 7</td>
		</tr>
		<tr>
			<td>5</td>
			<td colspan="4">Is the leaf once compound? 
			Is the leaf twice compound?</td>
			<td>Green Ash 
			Honeylocust</td>
		</tr>
		<tr>
			<td>6</td>
			<td colspan="4">Is the leaf pinnately lobed? 
			Is the leaf palmately lobed?</td>
			<td>Bur Oak 
			Row 8</td>
		</tr>
		<tr>
			<td>7</td>
			<td colspan="4">Does the leaf have teeth on the margin? 
			Does the leaf NOT have teeth on the margin?</td>
			<td>Row 9 
			Redbud</td>
		</tr>
		<tr>
			<td>8</td>
			<td colspan="4">Does the leaf have 3 – 5 deep lobes with opposite leaf arrangement? 
			Does the leaf have 3 – 5 shallow lobes with alternate leaf arrangement?</td>
			<td>Silver Maple 
			Sycamore</td>
		</tr>
		<tr>
			<td>9</td>
			<td colspan="4">Does the leaf margin have double teeth, elliptical shape and asymmetrical at the base? 
			Does the leaf have a single teeth margin?</td>
			<td>American Elm 
			Cottonwood</td>
		</tr>
	</tbody>
</table>
Table 1. Tree Identification Dichotomous Key.
<table cellpadding="0" cellspacing="0" fo:keep-together.within-page="always">
	<tbody>
		<tr>
			<td>Unknown Sample</td>
			<td colspan="4">Species</td>
		</tr>
		<tr>
			<td>1</td>
			<td colspan="4"></td>
		</tr>
		<tr>
			<td>2</td>
			<td colspan="4"></td>
		</tr>
		<tr>
			<td>3</td>
			<td colspan="4"></td>
		</tr>
		<tr>
			<td>4</td>
			<td colspan="4"></td>
		</tr>
		<tr>
			<td>5</td>
			<td colspan="4"></td>
		</tr>
		<tr>
			<td>6</td>
			<td colspan="4"></td>
		</tr>
		<tr>
			<td>7</td>
			<td colspan="4"></td>
		</tr>
		<tr>
			<td>8</td>
			<td colspan="4"></td>
		</tr>
		<tr>
			<td>9</td>
			<td colspan="4"></td>
		</tr>
		<tr>
			<td>10</td>
			<td colspan="4"></td>
		</tr>
	</tbody>
</table>
Table 2. A blank table to fill out tree species for each unknown leaf sample.
<table align="center" border="1" cellpadding="0" cellspacing="0" fo:keep-together.within-page="always">
	<tbody>
		<tr>
			<td>Tree Sample Number</td>
			<td>Leaf Arrangement (opposite, alternate, or whorled)</td>
			<td>Circumference at 4½ feet above grade (inches)</td>
			<td>Diameter at 4½ feet above grade (inches) *calculated</td>
			<td>Land Use</td>
			<td>Species</td>
			<td>Notes</td>
		</tr>
		<tr>
			<td>1</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>2</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>3</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>4</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>5</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>
Table 3. A blank data sheet to fill out leaf arrangement, circumference, dbh, land use, species, and notes.

Understanding the benefits trees provide for a community is important. Converting this benefit to a monetary value or ecosystem services value allows for a concrete understanding of exactly the role trees play in an ecosystem. Trees are important for health, the economy, and the environment, and once this is realized, a discussion about ways to protect the trees and increase their benefits can begin. As trees age and grow, their benefits increase. This provides a reason to protect mature trees (Figure 17...

tree identification: how to use a dichotomous key

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
A dichotomous key is a tool that identifies items in nature, such as leaves. This method is based on the idea of choosing between two characteristics. The word dichotomous comes from two Greek words that mean &#8220;to divide into two parts.&#8221; In a dichotomous key for leaf identification, each pair of phrases describes different features of the leaf. Only one of the phrases correctly applies to the leaf being keyed out. The correct phrase leads to the next pair of phrases, or states the name of the tree from which the leaf came. Using a field guide to trees and the iTree National Tree Benefits Calculator helps to identify trees in a field investigation, which shows the significance of trees in terms of their environmental benefits, such as storm water management, increasing property value, energy efficiency, air quality, and carbon sequestration.

Table 4 contains the correctly identified leaves for the identification of a set of 10 unknown species.
Results for the field investigation will vary depending on the samples collected. Representative results for trees found in the Chicagoland area (zip code 60031) can be found in Table 5.
The results for using the Tree Benefit Calculator can be found in Table 6. This calculator provides an estimation of the benefit...

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
A dichotomous key is a tool that identifies items in nature, such as ...

Dichotomous keys are commonly used in science to identify items in nature, including trees. Users progress through sets of two-choice questions, leading to the identity of the sample.In a dichotomous key, questions are posed as paired phrases or questions, in which only one can be correct. The correct phrase then leads to the next question or phrase, until finally, after a number of steps, it leads to identification of the item being keyed out.For tree identification by dichotomous key, users study the features of leaves and leaf arrangement, and move though the paired phrases until reaching identification of the tree the leaf came from.This video will illustrate the layout of a dichotomous key, how to use it, and some of the leaf features used in dichotomous keys for tree identification.Leaves are very characteristic of individual tree species, and are commonly used to identify trees. Leaf shape, arrangement, margins, and multiple other characteristics can be taken into account when identifying a tree sample.Broadleaf trees are common in the United States, and are characterized by leaves with wide blades that expose a large area for photosynthesis. Most broadleaves are deciduous, dropping their leaves in autumn.The second major tree type in the United States is the evergreen. These have needle or scale-like leaves, which generally stay on the trees year round. Needle-like leaves have little surface area for photosynthesis, and a thick waxy coating to prevent water loss, making needled evergreens well suited to areas where water conservation is important for survival.Leaf shape is tied to the evolutionary history of a tree species, and depending on the ecosystem demands, the leaf's needs to maximize sunlight capture while minimizing heat absorption and water loss. Overall leaf shape is a trait often used to categorize broadleaves in dichotomous keys.Leaves may be categorized as heart shaped, triangular, lance, ovate, or obovate. Other shaped leaves occur, but these are most common. Leaf arrangement on the twig is another characteristic used in key identification of trees. Opposite leaves are those occurring in pairs at the nodes, usually displaying adjacent tiers at right angles to minimize overlap. Alternate leaves, the most commonly seen arrangement, are staggered, not directly across from one another, and often arranged in a spiral along the twig. Whorled arrangements have three or more leaves occurring at a single node.The edge of the leaf, or leaf margin, may also provide features to aid identification. They may be smooth, have projections, teeth, or undulations. A wavy or bumpy edge is called rounded or sinuate. Again, this may be related to environmental conditions. In colder climates, native trees tend to have larger and more teeth.With broadleaf trees, leaves may be categorized as simple or compound. Simple leaves have one leaflet, a petiole or "stalk", and a bud at the base of the petiole. Compound leaves have two or more leaflets and a bud at the base of the petiole. Further, once-pinnately compound leaves have one main petiole and leaflets arranged on each side of the petiole. Twice-pinnately compound leaves have one main petiole, and secondary petioles arranged on either side of the main petiole. This can be used to check the difference between a leaf and a leaflet; if there is no bud where it attaches to the stem, it is a leaflet, not a leaf.Now that we are familiar with some of the traits of common trees and leaves, and some categories used for tree identification, let us walk through the use of a key.Before attempting to identify leaf samples, it is necessary to first become familiar with the traits and the categories examined within the key itself.The first question in the key asks whether the leaf specimen is needlelike or scalelike, or if it is broadleaf. The first two are categorized as evergreen, and the second as deciduous. If the answer is "needlelike or scalelike" proceed to row 2 of the key. If it is "broadleaf", proceed to row 3.Row 2 relates to needlelike or scalelike leaves, and asks which of these best describes the sample. Needlelike leaves have very little surface area, and have a thick, waxy coating to prevent excessive water loss. Scalelike leaves also have narrow surface area, but are comprised of small, individual scales. If the leaves are scalelike, the key states that the specimen is a Red Cedar. If the leaves are needlelike, the key states that the specimen is a Scotch Pine.Question 3 asks if the leaf is simple or compound. Simple leaves are those with one leaflet per petiole or stem, and a bud at the base of the petiole. Compound leaves are those with two or more leaflets, a petiole, and bud at the base. If the leaf is simple, move to row 4, and if compound, to row 5.The fourth question asks if the leaf is lobed or unlobed. Lobed leaves are those with projections that give the leaf shape. Unlobed leaves have a consistent leaf edge. If the leaf is lobed, the key instructs to move to row 6. For unlobed leaves, row 7 should be consulted next.Row 5 follows on from question 3 and asks if the leaf is once or twice compound. Once-compound leaves have two or more leaflets arranged pinnately on each side of the petiole. A twice-compound leaf has one main petiole, and then secondary petioles arranged on each side of the main petiole. This is a terminal question, with once-compound leaves listed as belonging to Green Ash, and twice-compound as Honeylocust.Question 6 deals with lobed broadleaves. Is the leaf pinnately or palmately lobed? Pinnate lobes are those where the lobes all attach to a central axis or vein. Conversely, in palmate leaves, the lobes all radiate from a single point. For pinnately lobed leaves, the leaves belong to Bur Oak. For palmately lobed leaves, the key moves on to Row 8.In row 7, the key asks if the leaf samples have teeth on the margin. Teeth are classed as continuous and serrate, versus a smooth leaf, which has no serrate or pointed projections on the margin. Toothed samples lead on to Question 9, and untoothed are classified as Redbud leaves.Question 8 asks if the leaf samples have 3-5 deep lobes with opposite leaf arrangement, or 3-5 shallow lobes with alternate leaf arrangement. Deep lobes are those that extend far into the leaf surface, and opposite leaf arrangement is seen when leaves occur in pairs at the nodes. Shallow lobes are those that extend less into the leaf surface, and alternate leaf arrangements are those in which leaves are staggered, or not directly across from one another. Deep lobes and opposite leaf arrangement leads to Silver Maple, whereas shallow lobes and alternate arrangement leads to Sycamore.Finally, question 9 asks if the leaf margin has double teeth, elliptical shape, and is asymmetrical at the base, or if instead it has a single toothed margin. If the former is true, the sample is identified as American Elm, and if the leaf has a single toothed margin, it is from a Cottonwood tree.Now, use the leaves pictured along with the dichotomous key to practice identification.After examination of the key and the characteristics described, field identification of trees can be carried out. First, select a tree to be identified. Collect one representative leaf sample from the tree, and affix it to herbarium paper using glue.Next, note whether the leaves have an alternate or opposite arrangement on the stems, and record this on the herbarium sheet. Measure the diameter at breast height of the tree in inches by taking the circumference of the tree at 4.5 ft above the existing grade, and calculate the diameter. Record the circumference and diameter.Note what type of land use is nearest to the tree: residential, small commercial, industrial, park or vacant land. Using the dichotomous key, identify the leaf samples and record the tree species on the herbarium sheet.Tree identification has many practical applications, and dichotomous keys are useful and practical tools for quick identification.Tree identification is an important first step in understanding the benefits specific trees or tree species provide in a community environment. Using tree identification data, and the National Tree Benefits Calculator, scientists and urban planners can use tree data to inform decisions about building, infrastructure, or planting strategies to maximize benefits to health and the environment, and decrease energy consumption.Dichotomous keys are commonly used to identify many different types of organisms. For example, they can be used to identify anything from species of venomous snake, to insect pests of citrus trees, or types of aquatic plant. This technique can allow users unfamiliar with a specimen to key out an identify subjects simply in the field or laboratory setting.The ability to identify trees or their pests by key can be extremely useful in pest or disease control. For example, the Asian Longhorned Beetle is becoming an increasingly common pest in US woodlands. An insect identification key can be used to identify and distinguish these from other native longhorn beetles, and also identify at-risk tree species in woodlands where this pest has been found. In turn, this can help to curb the spread of this highly invasive pest.You've just watched JoVE's introduction to identifying trees using a dichotomous key. You should now understand how dichotomous keys work, and how to apply a dichotomous key to tree identification. Thanks for watching!

Education

JoVE Science Education

Environmental Sciences

leaf traits and tree id with a key

Leaf traits can help students identify trees with a dichotomous key. A dichotomous key is a nature ID tool that works by choosing between two characteristics at each step. The word dichotomous comes from two Greek words that mean &quot;to divide into two parts.&quot;

Leaf Traits and Tree ID With a Key

Leaf traits can help students identify trees with a dichotomous key. A dichotomous key is a nature ID tool that works by choosing between two characteristics at each step. The word dichotomous comes from two Greek words that mean "to divide into two...

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environmental science

This collection utilizes an interdisciplinary approach to explore and evaluate environmental systems with topics ranging from soil and water contaminants, invasive species, alternative energy and forestry. 

Learn how a dichotomous key uses leaf traits to identify trees and why tree ID matters in field investigations and environmental benefits.

Leaf Traits and Tree ID With a Key | JoVE K12

Next Generation Science Standards

High School

Earth and Space Science

Earth and Human Activity

HS-ESS3-4

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New York State Science Learning Standards

Life Science

Structure and Function

HS-LS1-3.

interdependent-relationships-in-ecosystems

Interdependent Relationships in Ecosystems

HS-LS2-2.

Earth and Space Sciences

Human Sustainability

HS-ESS3-1.

HS-ESS3-3.

HS-ESS3-4.

HS-ESS3-6.

Georgia Standards of Excellence

SEV4.

SEV4.a

Overview

Principles of Tree Identification Using a Dichotomous Key

Preparing to Use the Dichotomous Key

Field Investigation

Applications

Summary

What are Populations and Communities?

Populations are groups of individuals of the same species that inhabit a shared environment. Communities include multiple co-existing, interacting ...

Distribution and Dispersion

Ecology is the study of how organisms interact with their environment and with one another. An important aspect of ecology is understanding where species ...

Life Histories

Constrained by limited energy and resources, organisms must compromise between offspring quantity and parental investment. This trade-off is represented ...

Ecological Niches

All organisms have a position within an ecosystem. The complete set of living and nonliving factors&#x2014;including food resources, climate, and ...

Ecological Succession

Ecological succession is influenced by the processes of facilitation, inhibition, and toleration. Facilitation occurs when early successional species ...

What is an Ecosystem?

Overview

An ecosystem is the interaction between all abiotic and biotic factors in an environment and can be classified as terrestrial or aquatic. ...

3. Construct an explanation of how biotic and abiotic factors affect biodiversity and populations in ecosystems. Examples: Explain how factors such as biomass, reproductive strategies, succession, climate, and geography affect an organism's chances of surviving and reproducing through successive generations.

9-12.EVS.2.3

Keystone Species

Measures of species biodiversity, such as richness (i.e., the number of species present) and evenness (i.e., their relative abundance), describe an ...

What is Biodiversity?

Biodiversity describes the variety of living things at multiple organizational levels: genetic, species and ecosystem diversity. Species diversity ...

Threats to Biodiversity

There have been five major extinction events throughout geological history, resulting in the elimination of biodiversity, followed by a rebound of species ...

Analysis of Earthworm Populations in Soil

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Using mustard, Lumbricus terrestris earthworm populations can be sampled ...

water-quality-analysis-via-indicator-organisms

Water Quality Analysis via Indicator Organisms

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba -The University of Arizona
Demonstrating Author: Luisa Ikner
Water quality analysis monitors ...

What is Conservation Biology?

Conservation biology is a scientific field that focuses on the preservation of biodiversity in order to protect ecosystems while meeting the needs of the ...

Measuring Biodiversity

Diverse ecosystems are important for the health of the planet and our survival as humans; it is therefore incredibly important for us to understand and ...

Community Diversity

Populations do not live in isolation; thus, every population interacts with others in certain ways. These interactions give rise to a network of ...

a. Support a claim that biodiversity is a natural resource which fosters ecosystem resilience, including the role of keystone, invasive, native, endemic, and indicator species.

9-12.EVS.2.3.a

gis-software-hardware-and-sources-of-gis-data

GIS Software, Hardware, and Sources of GIS Data

A Geographic Information System (GIS) combines specialized software and hardware to effectively manage, analyze, and present spatial and related data. GIS ...

Manipulation and Analysis

GIS manipulation and analysis functions are vital for decision-making and planning. These activities range from data retrieval tasks, such as selecting ...

Using GIS to Investigate Urban Forestry

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Urban forests broadly include urban parks, street trees, landscaped ...

using-topographic-maps-to-generate-topographic-profiles

Using Topographic Maps to Generate Topographic Profiles

Source: Laboratory of Alan Lester - University of Colorado Boulder
Topographic maps are &#34;plan-view&#34; representations of Earth&#39;s ...

Tree Survey: Point-Centered Quarter Sampling Method

A number of methods are available for sampling forest communities. Point-centered quarter is one such method. It is used to gather information on the ...

Introduction to Microbial Ecology

Microbial ecology examines the complex web of interactions and diversity among microorganisms within various ecosystems. This field seeks to understand ...

Species Distribution and Biogeography

Simulating Colonization and Extinction on Islands
ExpandForm groups of three. One member of the group will simulate colonization by throwing balls into ...

Freshwater Microbial Ecology

Freshwater systems such as streams, rivers, and lakes exhibit distinct physical and biological characteristics that influence their microbial communities. ...

Soil Microbial Ecology

Soil microbial ecology is defined by highly diverse, spatially structured communities that drive nutrient cycling, organic matter turnover, and overall ...

b. Analyze and interpret data collected through geographic research and field investigations to describe Alabama's biodiversity by region. Examples: Use relief, topographic, and physiographic maps or information on rivers, forests, and watersheds to investigate species distributions and diversity.

Leaf Traits and Tree ID With a Key

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