How to Differentiate Between Species and Cultivar Names

In the world of botany and horticulture, understanding the nomenclature of plants is crucial for accurate identification, communication, and documentation. Two terms that frequently appear in plant naming are species and cultivar. While both relate to the classification and naming of plants, they serve very different purposes and follow distinct rules. This article delves into how to differentiate between species and cultivar names, explaining their definitions, conventions, and practical implications for gardeners, botanists, and plant enthusiasts alike.

Understanding Species in Plant Nomenclature

What is a Species?

A species is the fundamental unit of biological classification in taxonomy. It represents a group of organisms that share common genetic characteristics and are capable of interbreeding to produce fertile offspring. In plants, species are often defined based on a combination of morphological features, reproductive compatibility, ecological niche, and genetic similarity.

For example, Rosa canina is a species name belonging to the wild rose commonly known as dog rose.

How Are Species Named?

Species names follow the binomial nomenclature system developed by Carl Linnaeus in the 18th century. This system assigns each plant a two-part Latinized name:

• Genus name: The first part, capitalized (e.g., Rosa), which groups related species together.
• Specific epithet: The second part, lowercase (e.g., canina), that distinguishes one species within the genus.

Together, they form the full species name (Rosa canina), which is always italicized or underlined when handwritten.

Characteristics of Species Names

• Written in Latin or Latinized words.
• Composed of two parts: genus and specific epithet.
• Italicized in print; genus capitalized, species lowercase.
• Universal across languages.
• Stable but can be revised with new scientific insights.

What is a Cultivar?

Definition of Cultivar

A cultivar (short for “cultivated variety”) is a plant selection that has been produced or maintained through cultivation by humans due to its desirable traits such as flower color, fruit size, disease resistance, or growth habit. Unlike species, cultivars are not naturally occurring groups but are deliberately bred or selected variants.

For example, Rosa ‘Peace’ refers to a specific cultivated rose variety prized for its unique color pattern.

Naming Conventions for Cultivars

Cultivars are named according to the guidelines set by the International Code of Nomenclature for Cultivated Plants (ICNCP). These rules differ from those used for wild plant taxonomy.

Key points include:

• Cultivar names are non-Latin and usually in modern languages.
• Enclosed within single quotation marks (e.g., ‘Peace’).
• Not italicized but capitalized as proper nouns.
• Typically follow the genus or species name (e.g., Rosa ‘Peace’ or Rosa canina ‘Alba’).

Examples of Cultivar Names

• Acer palmatum ‘Bloodgood’ , A Japanese maple cultivar with dark red leaves.
• Lavandula angustifolia ‘Hidcote’ , A lavender cultivar known for compact growth.

Key Differences Between Species and Cultivar Names

Understanding how to differentiate between species and cultivar names hinges on recognizing their naming conventions and biological significance.

How to Identify Species vs. Cultivar Names in Practice

When confronted with a plant name, you can identify whether it is a species or cultivar by following these steps:

1. Look at the Format

• If the name consists of two Latin words in italics (or underlined), it is likely a species name.
• If there is an additional non-Latin word enclosed in single quotation marks following the species or genus name, that word denotes the cultivar.

2. Check Capitalization

• The genus is always capitalized; species epithet is lowercase.
• The cultivar name is capitalized but not italicized.

3. Identify Language Style

• Species names use Latin or Latinized terms.
• Cultivars have names derived from modern languages and often have commercial or descriptive names.

4. Consider Context

If you see just one binomial Latin name (e.g., Helianthus annuus), it refers to a species, the common sunflower in this case.

If you see something like Helianthus annuus ‘Autumn Beauty’, this indicates a particular cultivar selected for traits like flower color or size.

Why Is Distinguishing Between Species and Cultivars Important?

Recognizing the difference has practical implications across several fields:

Botanical Research and Conservation

In scientific research and conservation efforts, precise identification of species ensures correct data collection about biodiversity, distribution, and ecological roles. Confusing cultivars with wild species could lead to inaccurate assessments of natural populations.

Horticulture and Gardening

For gardeners and landscapers purchasing plants, knowing whether they’re obtaining a species or a particular cultivar affects expectations regarding plant behavior like hardiness, bloom time, size, and disease resistance.

Legal Protection and Plant Breeding

Cultivars sometimes have intellectual property rights attached to them such as patents or plant breeders’ rights. Accurate naming helps protect these legally.

Trade and Commerce

Nurseries label plants using standardized nomenclature to avoid customer confusion. Mislabeling plants, calling cultivars by their species name only, can lead to dissatisfied consumers when plants don’t perform as expected.

Additional Naming Categories Related to Species and Cultivars

While distinguishing between species and cultivars forms the core understanding, other botanical categories exist:

Subspecies and Varieties

Sometimes within a species there are naturally occurring subdivisions such as subspecies (subsp.) or varieties (var.) that indicate populations with slight morphological differences adapted to different regions.

Example: Pinus nigra subsp. salzmannii

These ranks also follow Latin naming conventions but differ from cultivars because they occur naturally rather than through human selection.

Hybrids

Hybrids arise from crossing two different species or genera. Their names often include an “x” symbol indicating hybrid origin (e.g., Nothofagus x leoni).

Cultivars can also be hybrids that have been selected for horticultural purposes.

Summary: Quick Tips on Differentiation

• Species names: Two-part Latin names italicized (Genus specific epithet), representing natural plant groups.
• Cultivar names: Non-Latin words capitalized within single quotes following genus/species name (Genus ‘CultivarName’), representing human-selected variants.
• Formatting matters, italicization vs regular typeface; quotes around cultivar names.
• Knowledge of these differences aids accurate communication about plants in science, gardening, commerce, and conservation.

By mastering these distinctions between species and cultivar names, enthusiasts at all levels can improve their plant identification skills, enhance their gardening success, participate more effectively in botanical discussions, and contribute meaningfully to preserving botanical diversity. Whether you’re labeling your garden plants or conducting formal research, understanding plant nomenclature is essential for clarity and precision.