Cultigen vs. Cultivar: Understanding Human-Altered Plants
In the worlds of agriculture, horticulture, and forestry, the plants we interact with most are rarely the same as those found in the untouched wild. Through centuries of intentional selection, breeding, and genetic modification, humans have shaped plant life to serve specific commercial and nutritional needs. In scientific terms, these human-influenced plants are known as cultigens. While often confused with the term "cultivar," understanding the distinction between these two concepts is essential for anyone studying botany or professional gardening.
A cultigen (derived from the Latin cultus, meaning "cultivated," and gens, meaning "kind") is any plant that has been deliberately altered or selected by humans. This transformation can occur through various methods, including plant breeding, genetic modification, graft-chimaeras, or simple selection from wild populations. Whether these plants are grown in a controlled greenhouse, planted in the wild, or have become naturalized in a new environment, they remain classified as cultigens.
Key Facts
- Definition: A cultigen is a plant or group of plants shaped by intentional human activity.
- Origin: The term was coined in 1918 by American horticulturist Liberty Hyde Bailey.
- Distinction: A cultigen is a broad category, whereas a cultivar is a specific formal rank within that category.
- Naming: Cultigens are governed by different sets of rules depending on whether they are treated as botanical species or cultivated entities.
- Examples: Common cultigens include maize (Zea mays) and banana (Musa acuminata).
The History and Origin of the Term
The concept of the cultigen was born from a need to categorize plants that did not fit neatly into the traditional Linnaean hierarchical classification. In 1918, Liberty Hyde Bailey, a prominent American botanist and co-founder of the American Society for Horticultural Science, identified a gap in botanical nomenclature. He noted that there were two distinct "kinds" of plants: indigens (plants of known native habitat) and cultigens.
Bailey described cultigens as domesticated groups whose exact origins might be unknown or indefinite, possessing characteristics that separate them from their wild counterparts. While his definitions evolved over the following years—at one point restricting the term to the rank of species—the core idea remained: cultigens are plants that arise under the hand of man.
Ancient Perspectives on Cultivation
The distinction between wild and cultivated plants is not a modern invention. Botanical historian Alan Morton suggests that ancient Greek botanists, including Theophrastus (often called the "Father of Botany"), were interested in this distinction. Theophrastus recognized that human action, rather than divine intervention, produced cultivated plants from wild ones. He even observed that certain cultivated fruit trees would lose their specific qualities if grown from seed, hinting at an early understanding of genetic constitution.
Cultigen vs. Cultivar: What is the Difference?
One of the most common points of confusion in horticulture is the difference between a cultigen and a cultivar. While the terms are related, they operate at different levels of classification.
The Broad Category: Cultigen
In botanical literature, "cultigen" is a general-purpose term. It encompasses any plant that has been human-selected, such as bread wheat (Triticum aestivum). A cultigen might have a formal scientific species name, or it might simply be a plant known only through cultivation without a formal taxonomic description.
The Specific Rank: Cultivar
A cultivar (a term Bailey introduced to distinguish cultivated varieties from botanical varieties) is a formal category defined by the International Code of Nomenclature for Cultivated Plants (ICNCP). While all cultivars are cultigens, not all cultigens are cultivars. The ICNCP recognizes three specific categories for naming cultivated plants:
- The Cultivar: A specific plant variety maintained through cultivation.
- The Group: A collection of cultivars with shared characteristics.
- The Grex: A term used specifically in the classification of orchids.
It is important to note that the ICNCP does not recognize trade names or marketing designations as scientifically valid names, though it provides guidance on how to present them.
Summary of Botanical Classifications
| Term | Scope | Primary Driver | Naming Authority |
|---|---|---|---|
| Indigen | Wild/Native plants | Natural evolution | International Code of Nomenclature for algae, fungi, and plants |
| Cultigen | Broad category of all human-altered plants | Human selection/breeding | General botanical usage |
| Cultivar | Specific, named horticultural entities | Deliberate propagation | International Code of Nomenclature for Cultivated Plants (ICNCP) |
Frequently Asked Questions
Is a cultivar the same as a species?
No. A cultivar is a subordinate rank to a species. While some cultigens are treated as species (like maize), a cultivar is a specific selection that exists within or alongside those broader categories.
Can a cultigen exist in the wild?
Yes. Cultigens can escape cultivation and become naturalized in the wild. In some cases, they may even breed with indigenous plants, creating new progeny that can later be brought back into cultivation.
Why do we need different naming codes for plants?
Because plants in cultivation are often maintained by human intervention rather than natural processes, the traditional botanical codes (used for wild species) do not always account for the rapid changes and specific groupings found in agriculture and horticulture. The ICNCP was created to provide a stable system for these human-managed plants.
What determines if a plant is a cultigen?
The primary factor is intentional human activity. If a plant's current characteristics are the result of deliberate selection, breeding, or genetic modification by humans, it is classified as a cultigen.
Does every cultigen have a formal name?
No. While many important cultigens like bananas have scientific names, some plants resulting from breeding or grafting may have no commercial value and therefore have not been formally named according to ICNCP principles.