Botanical rules and nomenclatures

Botanical nomenclature has a long history, but most modern rules and conventions date back to the publication in 1753 of “Species Plantarum” by Carl Linnaeus (Carl von Linné), a Swedish naturalist. This work introduced the binomial system of nomenclature, which is now universally used in biology.

The binomial system gives each species a unique scientific name that consists of two parts: the genus name, which is shared with other related species, and the specific name or specific epithet, which is unique to each species. For example, for the human species, Homo sapiens, “Homo” is the genus and “sapiens” is the specific epithet. Names are generally based on Latin or Greek, although they may be derived from other languages.

Botanical nomenclature is governed by the International Code of Nomenclature for algae, fungi, and plants (ICN). There are also similar codes for other groups of organisms, such as the International Code of Zoological Nomenclature (ICZN) for animals.

Codes evolve over time to account for new discoveries and scientific advancements. For example, with the advent of molecular biology, classifications based on genetic relationships have become increasingly important, sometimes leading to changes in nomenclature.

Carl Linnaeus (1707-1778), the inventor of the binomial system[/caption>

This nomenclature is essential in botany (but also for the rest of biology) for several reasons:

• Communication: When scientists around the world use the same name to refer to a specific plant, it facilitates communication and the exchange of information. This is particularly important in scientific research, where results must be reproducible and accessible to an international audience.
• Precision: The binomial system of nomenclature allows for the precise and unique identification of each species. This avoids confusion that could arise from the use of common names, which often vary from region to region and can be applied to several different species. For sectors such as agriculture, horticulture, forestry, pharmacology, etc., precise species identification is essential. For example, knowing the correct species of plant can be crucial for food production, medicine, material production, and many other aspects of human society.
• Classification: Botanical nomenclature often reflects the evolutionary relationships between plants. Plants of the same genus are more closely related to each other than to plants of other genera. This organisation helps scientists understand the evolutionary history of plants and predict the characteristics of unstudied plants based on their classification.
• Conservation: Botanical nomenclature also aids in the conservation of species. By having a universally recognised system for identifying plants, efforts to protect endangered species can be better coordinated across international borders.

Please note: for now, in botany, there are no standardised names in French, unlike in ornithology, for example. Plant names in French can thus be vernacular or common (usual names in a certain language, national or local, or even a dialect) or vulgar (translation into everyday language of the Latin name or a vernacular name). Although often confusing, these names are still widely used and hold considerable importance in ethnolinguistic heritage. After all, we ourselves refer to a daisy flower (“which blooms at Easter”) and not to the inflorescence of a Bellis perennis.

A Latin name to be understood worldwide

A subspecies is a taxonomic rank in botany, situated between species and variety. Higher than variety, a subspecies is used to designate groups of plants within a species that have distinct characteristics and a particular geographical distribution, but are capable of interbreeding.

These subgroups generally have specific adaptations to certain environmental conditions or are geographically isolated from other groups within the species, leading to distinct differences in their morphology or behaviour.

The name of the subspecies is always written in lowercase and is preceded by the term “subsp.” (or “ssp.” in abbreviation) placed between the species name and the subspecies name. For example, in “Helichrysum italicum subsp. microphyllum” (Italian Everlasting or Curry Plant), “Helichrysum italicum” is the species name, and “microphyllum” is the subspecies name.

It is worth noting that the boundaries between variety, subspecies, and species can be blurred and are often subject to debate among botanists and biologists. Classifications can change over time with advancements in scientific understanding.

In botany, a “variety” is a taxonomic rank below species. It is used to designate populations of plants within a species that exhibit minor but consistent differences from the species norm. These differences may relate to colour, shape, size, or other morphological characteristics. These populations are generally naturally occurring and are capable of interbreeding with other varieties within the same species.

The name of the variety is always written in lowercase and is preceded by the term “var.” placed between the species name and the variety name. For example, taking cabbage, it is a variety of Brassica oleracea (common cabbage) and should be written as: Brassica oleracea var. capitata.

It is important to note that the term “variety” in botany has a specific technical meaning and should not be confused with the common usage of the term in horticulture or agriculture, where it is often used interchangeably with “cultivar” to refer to variants of a plant that are clonally propagated to maintain specific characteristics.

A “cultivar” is a term used in botany and horticulture to refer to a plant selected for desirable characteristics that are maintained during propagation. The term “cultivar” is a contraction of “cultivated variety”.

A cultivar may be selected for many reasons, including a particular size, flower colour, resistance to certain diseases, tolerance to specific environmental conditions, or high yield. Once a plant is selected as a cultivar, it is generally propagated clonally (by propagation by cuttings, grafting, division, etc.) rather than by seeds, to ensure that the descendant plants retain the desirable characteristics of the parent.

In terms of nomenclature, the name of a cultivar is generally written in lowercase, enclosed in single quotation marks, and placed after the scientific name of the species. For example, Acer palmatum ‘Atropurpureum’ is a cultivar of Japanese maple with red leaves.

It is important to note that cultivars are often the result of human horticultural and agricultural efforts, whereas taxonomic ranks such as species, subspecies, and varieties are generally used for groups of plants that have naturally differentiated in the wild.

Did you know?: A “nativar” is a relatively recent term in the field of horticulture. It is used to describe a cultivar derived from a native or indigenous plant. These plants are often chosen and propagated because they possess desirable characteristics, such as beautiful flowering, colourful foliage, or resistance to certain diseases, while also retaining many traits of their wild native parents: for example, the Quercus robur ‘Fastigiata’. In terms of nomenclature, nativars are generally designated in the same way as other cultivars, with the cultivar name in lowercase, enclosed in single quotation marks, and placed after the scientific name of the species. However, please note that the use of the term “nativar” is less standardised and accepted than terms like “species” or “cultivar”, and it may not be recognised or used in the same way by all botanists or gardeners.

The Special Case of Hybrids

In botany, a hybrid is the result of crossing two plants of different species or genera. The naming of hybrids follows certain rules and conventions depending on the type of hybrid.

1. Interspecific Hybrids: These hybrids are the result of crossing two different species within the same genus. The name of the hybrid is generally formed by combining the genus name with a specific hybrid epithet, often “x hybrida”. For example, Petunia × hybrida is a hybrid of different species of Petunia. Sometimes, the names of the two parent species are combined to form the specific epithet.
2. Intergeneric Hybrids: These hybrids are the result of crossing two plants of different genera. The name of the hybrid is a blend of the names of the two parental genera. For example, the Fatshedera (x) lizei is a hybrid between a Fatsia and a Hedera (ivy).

3. Cultivated Hybrids: These hybrids are often created in horticulture. They can be named like other cultivars, with a cultivar name placed after the scientific name of the species or hybrid, usually in single quotation marks. For example, Rosa × hybrida ‘Peace’ (synonymous with ‘Madame A. Meilland’ and ‘Gloria Dei’), a hybrid tea rose, is a specific cultivar of a rose hybrid.