Learn about Plant Taxonomy

Learn how to systematically describe, name, classify and identify plants.

This comprehensive 100-hour course provides a solid foundation in plant taxonomy.

Learn how to:

  • Name and classify plants
  • Describe plant parts
  • Identify plants
  • Record and analyse plant descriptions
  • Utilise taxonomic techniques
  • Recognise important plant families

Why study plant taxonomy?

Plant taxonomy is the science and practice of describing, naming, classifying and identifying plants. It is a skill which anyone working with plants should possess.

To attempt to select, grow, and use plants in any context without taxonomic skill is at best foolhardy, and at worst it can be outright dangerous.

There are also economic reasons for being able to identify plants. The development of new plant cultivars can be time-consuming and costly, but it is very important to commercial horticulture in order to improve continually the cultivars available in terms of productivity and quality. Anyone who devotes significant resources to developing a new cultivar needs to be able to establish and prove their commercial rights to that plant in order to obtain fair and profitable gain from their investment.

In this course, you will learn the fundamentals of plant taxonomy:

  • Rules of plant nomenclature
  • Plant classification systems
  • Plant parts and their role in plant identification
  • Methods of plant description
  • Taxonomic techniques
  • Important plant families

Duration: 100 hours


There are 10 lessons in this course:

1. Introduction to Taxonomy

  • Introduction to Plant Taxonomy
  • Scientific Vs. Vernacular Names
  • Linnaeus
  • Binomials
  • Uniformity
  • Protein Analysis
  • Ranks and Language
  • Ranks of Classification - KPCOFGS
  • Plant Phyla
  • Plant Families
  • Genus and Species
  • Latin Names
  • Gardener's Ranks
  • Hybrids
  • Subspecies
  • Varieties
  • Cultivars
  • International Code of Botanical Nomenclature
  • The Basic Ideas
  • Principle of Priority
  • Legitimate Naming
  • Recent Changes to the Code
  • International Code of Nomenclature for Cultivated Plants
  • Taxonomic Name Resolution Service
  • International Plant Names Index
  • Trademarks & Patents
  • Plant Breeders Rights
  • The Rise of Molecular Data
  • The Impact of Molecular Data

2. Describing Plant Parts

  • Habit
  • Stems
  • Hairs
  • Leaves
  • Compound and Simple Leaves
  • Leaf Shapes
  • Leaf Margins
  • Leaf Structure
  • Leaf Arrangements
  • Leaf Venation
  • Leaf Modifications
  • Roots
  • Root Modifications
  • Terminology
  • Flowers
  • The Inflorescence
  • Fruits
  • Dry Fruits
  • Fleshy Fruits
  • Compound Fruits
  • A Key to the Main Types of Fruits
  • Terminology

3. Recording & Analysing Plant Descriptions

  • Herbaria - Collecting and Preserving a Plant
  • Fresh Material
  • Arranging Plants for Pressing
  • Pressing Difficult Specimens
  • The Drying Process
  • Herbarium Specimens
  • Photographs
  • The Problem of Colour
  • The Law Relating to Plant Collecting
  • Describing a Plant on Paper
  • The Equipment You Need
  • Botanical illustration
  • Floral Diagrams
  • Floral Diagram Technique
  • Floral Formulae
  • DNA Barcoding
  • Process of Using DNA Barcoding for Plant Identification
  • Applications of DNA Barcoding
  • Chemical Analysis (Chemotaxonomy)

4. Taxonomic Techniques

  • The Advantages of Using Keys and Their Limitations
  • Using a Key
  • The Rules when Making a Key
  • Lamiaceae (Simplified Key)
  • Rules When Writing Couplets
  • Best Practice Points
  • Making a Key
  • Why Botanical Families are So Useful When Identifying Plants

5. Primitive Plants

  • The Bryophytes
  • Mosses
  • Liverworts
  • Hornworts
  • Vascular Plants or Tracheophytes
  • Vascular Tissue and Why it is Important in Evolution of Life on Earth
  • A glossary to help you
  • The Lycopodiopsida (or Lycophytes)
  • Clubmosses - Plants in the family Lycopodiaceae
  • Quillworts - Plants in the Family Isoetaceae
  • Spike Mosses or Lesser Clubmosses - Plants in the Family Selaginellaceae
  • The Euphyllophytes - The Seed Plants, Horsetails, and Ferns
  • The Seed Plants
  • Horsetails
  • The Ferns

6. Seed Plants

  • The Gymnosperms
  • The Cycads
  • Ginkgo
  • The Gnetidae
  • Welwitschiaceae
  • Gnetaceae
  • The Conifers
  • The Conifers’ Life History
  • The Cycads, Ginkgo, and Gnetidae - How they Differ from the Conifers
  • The Six Families of Conifers
  • The Angiosperms
  • Flowers and Why they are Important in Evolution of Life on Earth
  • The Flowering Plant’s Life History
  • The Diversity of Angiosperms

7. Phylogeny of Land Plants

  • Introduction
  • Darwin’s Tree of Life Metaphor - The Hidden Bond of Descent
  • Why Use DNA Sequences for Classification?
  • The Principle of Monophyly
  • The Phylogeny of Land Plants
  • The Major Changes in Flowering Plant Taxonomy
  • The End of the Monocot-Dicot Split
  • Finally, Some Resolution Within the Monocots
  • Some Surprises
  • Name Changes Resulting from the Increase in Evidence
  • When Applying the Principle of Monophyly Results in Name Changes
  • What We Can Learn From Phylogenies

8. Monocotyledons

  • Summary of Important Families
  • The Monocots - Significant Families
  • Arecaceae
  • Aizoaceae (syn. Ficoidaceae)
  • Dioscoraceae
  • Liliaceae
  • Orchidaceae
  • Iridaceae
  • Amaryllidaceae
  • Asparagaceae
  • Arecaceae
  • Pontederiaceae
  • Musaceae
  • Bromeliaceae
  • Poaceae
  • Cyperaceae
  • Juncaceae

9. Dicotyledons (Part I)

  • Important Dicot Families
  • Key to Selected Angiosperm Families
  • Lower-growing Soft-wooded Plants
  • Apiaceae
  • Asteraceae
  • Brasicaceae
  • Cactaceae
  • Crassulaceae
  • Euphorbiaceae
  • Gesneriaceae
  • Lamiaceae
  • Ranunculaceae
  • Solanaceae

10. Dicotyledons (Part 2)

  • Fabaceae - Papilionoideae, Mimosoideae, Caesalpinoideae
  • Fagaceae
  • Ericaceae
  • Magnoliaceae
  • Malvaceae
  • Myrtaceae
  • Ongaraceae
  • Rosaceae
  • Proteaceae
  • Rutaceae
  • Rubiaceae

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.


  • Explain how plants are classified, including both benefits of and contradictions within the scientific system as followed by horticulturists and botanical scientists across different parts of the world.
  • Examine and describe parts of a plant, both sexual and asexual, at various stages of the plant’s life cycle.
  • Process descriptive information about a plant using taxonomic techniques that involve processing that data to create a better understanding and/or record of that information.
  • Explain a variety of tools used in taxonomic work.
  • Explain the taxonomy of land plants that do not produce seeds.
  • Explain taxonomy of a range of significant, seed producing plants, including gymnosperms.
  • Explain the relationship between different types of plants (i.e. phylogeny), and how molecular information impacts on this in taxonomic considerations.
  • Differentiate between at least 10 different families of monocotyledon plants, through inspection and identification of a range of commonly shared characteristics within that family.
  • Differentiate between at least 10 different families of dicotyledon plants which predominantly contain lower growing soft wooded plants or herbs; through inspection and identification of a range of commonly shared characteristics within that family.
  • Differentiate between at least 10 different families of dicotyledon plants which predominantly contain woody trees and shrubs; through inspection and identification of a range of commonly shared characteristics within that family.



A vernacular name is a common or local name given to plants. These names are widely used among gardeners and non-horticulturists. There are some advantages to these vernacular names. For example, they are in the local language and thus easier to remember. They are also often descriptive with the description often indicating its appearance, a use, or danger. However, there are also drawbacks with common names. They can be very localised, and the same plant can have more than one common name. For example, the White Waterlily (Nymphaea alba) has many other common names, such as European White Waterlily, Waterlily, and White Lotus. Further confusion is created when the same common name is applied to different plants. For example, Nymphaea lotus is also called White Lotus and White Waterlily, along with other names like Egyptian Lotus, Egyptian Waterlily and White Egyptian Lotus. Another example is the common name Quince which is used for both Cydonia oblonga and Chaenomeles species.

Some common names are the same as the Latin name. For example, plants in the genus Euphorbia are often referred to by gardeners simply as euphorbias, although they can also be called spurges. Likewise, species in the genus Rhododendron are called rhododendrons, but some of them are called azaleas even though they are in the genus Rhododendron! Extreme confusion can result from the fact that “fritillary” is a common name for both a bulbous plant and a butterfly.

Scientific names on the other hand are all written in the Latin language. They can therefore be understood equally by anyone, anywhere, regardless of their native language. The Latin name ensures that people are referring to the exact same plant.


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