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What is a Dichotomous Key and How to Make One?

Written by: Danesh Ramuthi

Nov 28, 2023

Dichotomous Key

A dichotomous key is a scientific tool used to identify and categorize different organisms or objects based on a series of choices that lead the user to the correct name or classification. This key operates on a simple principle: at each step, it presents two mutually exclusive characteristics and the user selects the one that matches the item in question, leading to the next pair of choices until the final identification is made.

The primary purpose of a dichotomous key is to simplify the identification process, making it accessible and systematic for both experts and novices in fields like biology, ecology, and education. It is especially useful in the study of biodiversity, where distinguishing between similar species can be challenging.

Dichotomous keys are not just limited to the scientific community; they are also a valuable educational tool, fostering critical thinking and observational skills.

To create your own dichotomous key, you can utilize resources like the Venngage Dichotomous Key Maker and their Dichotomous Key Templates that can provide inspiration and a solid foundation for your own unique key, whether for educational purposes, research or personal interest.


Click to jump ahead: 

How to make a dichotomous key?

Creating a dichotomous key involves a methodical approach to classify organisms or objects based on observable characteristics. Here’s a brief step-by-step guide:

  1. Gather information: Start by collecting data about the organisms or items you wish to identify. Understand their key characteristics and how they differ from each other.
  2. Choose characteristics: Select obvious characteristics that are easy to observe and differentiate. These should be binary choices, like ‘has wings’ or ‘does not have wings’.
  3. Organize characteristics: Start with the most general characteristics and move towards more specific ones. This helps in narrowing down the options as you progress through the key.
  4. Create binary choices: Structure your key in a way that each step offers two choices based on the characteristics you’ve selected. For example, “Is the organism multicellular or unicellular?”
  5. Develop a dichotomous key diagram: Present your dichotomous key in a visually appealing format. You can create from scratch or use pre-designed editable templates.
  6. Test your key: Use your dichotomous key to identify known organisms or objects to ensure it leads to the correct identification. Adjust if necessary.
  7. Refine and expand: As you encounter new species or different organisms, continue to refine and expand your key to accommodate these additions.

What are the types of dichotomous keys?

Dichotomous keys, used for identifying organisms, come in various types, each with a distinct way of presenting information:

  1. Branched: It uses a tree diagram to graphically display statements, each offering two choices leading to different answers. It’s suited for identifying organisms one at a time, as the tree can’t branch downwards from both sides simultaneously​​.
  2. Nested: Known for its simplicity and ease of understanding, the nested style allows for classifying two organisms simultaneously. Answers to each statement are nested under the statement they respond to, often using indentations for clarity​​​​.
  3. Computer program: These dichotomous keys are presented as computer programs, making the identification process more user-friendly and interactive, akin to a quiz game. Users answer questions one at a time, progressively moving toward correct identification​​.
  4. Linked: In this style, questions and their respective answers are laid out in list form. Each answer directs the user to the next relevant question, requiring users to find the correct question to properly identify the organism

10 Dichotomous key examples

Dichotomous keys are versatile tools used in various fields to categorize and identify organisms or objects based on a series of choices. Let’s explore ten dichotomous key examples, each tailored to different subjects, demonstrating the breadth and adaptability of this method. 

From the natural world to the business sector, these examples showcase how dichotomous keys can be applied to both scientific and non-scientific realms.

Dichotomous key for animals

The dichotomous key for animals is a critical tool in zoology, aiding scientists, researchers and students in identifying various animal species. Such a key typically starts with broad questions about fundamental animal characteristics, like whether the animal is vertebrate or invertebrate.

Dark Animal Nested Style Dichotomous Key

As one progresses through the key, more specific attributes are considered, such as the type of skin covering (scales, fur or feathers), habitat preferences (aquatic or terrestrial) and dietary habits (herbivore, carnivore or omnivore).

Editable Dichotomous Key Examples

This systematic approach allows for a detailed and accurate classification, essential for studying animal behavior, ecological interactions and conservation efforts.

Free Dichotomous Key Example

It is particularly useful in regions with rich biodiversity, where distinguishing between closely related species is crucial for ecological balance and wildlife management.

Dichotomous Key for Animals

Plant biology dichotomous key

A Plant Biology Dichotomous Key is fundamental in botany for identifying various plant species. This key emphasizes physical and observable characteristics of plants, such as leaf patterns (simple or compound), flower structures (number of petals or symmetry) and types of seed dispersal mechanisms. 

Green Dichotomous Key for Trees

The key helps in distinguishing between plants that may look similar at a glance but have differing botanical features.

Pastel Food Branching Tree Dichotomous Key

It is an essential tool for botanists, horticulturists and nature enthusiasts, aiding in the classification of new species, understanding plant evolution and conserving rare or endangered flora.

In educational settings, it serves as a practical way for students to engage with the plant kingdom, enhancing their observational skills and deepening their appreciation of plant diversity.

Plant Biology Dichotomous Key

Dichotomous key for business

In business, a dichotomous key serves as a strategic tool for decision-making, customer segmentation and problem-solving. For example, in customer service, a dichotomous key can streamline the process of identifying a client’s needs or problems by leading the service representative through a series of binary questions.

Customer Support Dichotomous Key

This could include determining whether the issue is technical or non-technical, product-related or service-related and so forth. In marketing, such keys help in segmenting customers into distinct groups based on specific characteristics like buying behavior, preferences or demographic data, thus enabling more targeted and effective marketing strategies.

Neutral Simple Marketing Dichotomous Key

Even in product development and management, dichotomous keys assist in troubleshooting and quality control, ensuring a systematic approach to addressing challenges and enhancing product quality. Utilization of dichotomous keys in the business sector underscores its versatility and effectiveness in structuring complex processes into manageable, clear-cut steps.

Product Launch Dichotomous Key

What are the benefits of a dichotomous key?

Dichotomous keys offer significant benefits in various fields, primarily by simplifying the process of identifying and classifying organisms or objects. 

These keys break down complex identification tasks into straightforward, binary choices, making them accessible to both experts and novices. 

By focusing on obvious and physical characteristics, dichotomous keys provide a clear and systematic approach to distinguishing between different organisms or items, especially when dealing with large groups or similar species. 

Additionally, creating a dichotomous key helps in organizing characteristics methodically, facilitating correct and efficient identification. This is particularly useful in educational settings, where dichotomous keys aid in teaching students how to observe, compare and classify organisms. 

In scientific research, they enable the accurate classification of new species and the study of biodiversity. 

Furthermore, dichotomous keys, whether text-based or as a flow chart or branching tree diagram, are visually appealing and easy to follow, making them a practical tool in various subjects, from biology to business.

Dichotomous key FAQs

1. What would be something to not put in a dichotomous key?

When creating a dichotomous key, it’s important to avoid including subjective or ambiguous characteristics that can lead to inconsistent identifications.

Characteristics that are not easily observable or measurable, such as behavioral traits or genetic information, should generally be excluded, as they can complicate the identification process for users without specialized knowledge or equipment.

Additionally, avoiding overly complex or technical language is advisable to ensure the key remains accessible and useful for a broad audience.

2. What is a dichotomous key used for in science?

In science, a dichotomous key is primarily used for identifying and classifying living organisms, such as plants, animals and bacteria, based on their physical characteristics and observable traits. It serves as an essential tool in fields like biology, ecology and environmental science, where it aids in the study of biodiversity and the documentation of new species.

By providing a systematic approach to identification, dichotomous keys help scientists and students to accurately determine the species or classification of an organism, which is crucial for research, conservation and educational purposes.

The use of dichotomous keys in science exemplifies the practical application of taxonomy and systematics, the branches of science dedicated to classifying and naming living things.

3. How many choices does a dichotomous key provide at each step?

At each step, a dichotomous key provides exactly two choices. This binary system is the defining feature of dichotomous keys, hence the word “dichotomous,” which means divided into two parts. These choices typically present contrasting characteristics or features, guiding the user towards the next pair of options until a final identification is made.

The simplicity of having just two choices at each step makes the key user-friendly and efficient, allowing for a clear pathway through the process of identification. This approach ensures that even complex classifications can be broken down into manageable decisions, making dichotomous keys a preferred tool for identifying a wide range of organisms and objects in both scientific and educational contexts.

Bottom line

The dichotomous key is an invaluable tool, not just in the realm of science but across various disciplines. Its straightforward, binary choice structure simplifies the complex task of identifying and classifying organisms, making it an essential asset for researchers, educators and even businesses. 

With the insights provided in this comprehensive guide, along with practical examples, you’re well-equipped to create or utilize your own dichotomous key. 

To get started, check out Venngage Dichotomous Key Maker and explore their range of Dichotomous Key Templates, which offer a user-friendly platform to create a dichotomous key tailored to your specific needs.