Botanical Nomenclature – Principles, Rules, Ranks, Typification, author citation, rejection

What is Botanical nomenclature?

• Botanical nomenclature refers to the standardized process of naming plants according to internationally accepted rules, which helps ensure consistency and clarity in plant identification. This system is governed by the International Code of Nomenclature of algae, fungi, and plants (ICN), formerly known as the International Code of Botanical Nomenclature (ICBN). The ICN is managed by the International Association of Plant Taxonomy (IAPT), and it provides a framework for naming plant species and taxonomic groups.
• The primary goal of botanical nomenclature is to assign a correct and universally recognized name to each plant species. This naming process is crucial for maintaining stability and avoiding confusion in scientific communication. The historical development of botanical nomenclature can be traced back to early naming practices, which were often lengthy and cumbersome. The introduction of a systematic naming approach by Casper Bauhin in the early 17th century, who proposed a two-name system, laid the foundation for modern botanical nomenclature.
• Swedish naturalist Carl Linnaeus further refined this system in the 18th century, establishing the binomial nomenclature system. This system requires that every plant be given a unique two-part name, consisting of the genus and species. For instance, the white oak is scientifically named Quercus alba, while the sweet pea is referred to as Pisum sativum. Linnaeus’s method provided a clear and consistent way to name plants, which is still in use today.
• Botanical nomenclature is not just about assigning names; it also involves updating and revising names as taxonomic understanding evolves. Taxonomists, as experts in this field, are responsible for naming new taxa and ensuring that existing names are accurate and reflect current classifications. The Draft BioCode and PhyloCode are additional efforts aimed at creating unified naming systems for all living organisms, facilitating easier management of comprehensive biological databases.
• In summary, botanical nomenclature is a systematic approach to naming plants that ensures clarity and stability in scientific communication. It relies on internationally recognized rules and codes to provide consistent and accurate names for plant species and taxonomic groups.

Importance of scientific names

Scientific names are crucial for accurately identifying and classifying plants and organisms. Here are key reasons why they are essential:

• Precision and Clarity
  • Unambiguous Identification: Scientific names, derived from Latin or Greek, provide a precise identification for each species. For instance, the term “Rose” can refer to different plants, such as Rosa (Rosaceae) and Ipomoea (Convolvulaceae), which are not related despite sharing a common name.
  • Consistent Terminology: Unlike common names, scientific names are standardized globally. This avoids confusion that arises from local vernacular names that might vary or be ambiguous. For example, the term “Oak” could refer to Quercus (Fagaceae), Lithocarpus (Fagaceae), or even Grevillea (Proteaceae), depending on regional contexts.
• Universal Communication
  • Global Standardization: Scientific names adhere to international naming conventions, ensuring that researchers from different countries can communicate effectively about the same species without language barriers.
  • Stable Reference: Scientific nomenclature is governed by codes such as the International Code of Nomenclature (ICN), which maintains consistency over time. This stability is vital for accurate scientific discussion and documentation.
• Detailed Classification
  • Reflects Taxonomic Relationships: Scientific names indicate the family and genus to which a species belongs, providing insights into its evolutionary relationships. For example, the common name “Woodrose” can refer to different genera like Ipomoea (Convolvulaceae) and Primula (Primulaceae), whereas the scientific names clearly distinguish these plants’ taxonomic placements.
  • Facilitates Research: By providing a uniform naming system, scientific names enable efficient data collection and comparison across studies. This is particularly useful in fields like botany, ecology, and conservation.
• Avoids Miscommunication
  • Reduces Ambiguity: Common names can vary widely between languages and regions. For example, “Poison oak” refers to Rhus (Anacardiaceae) in some regions, but the same term might be used for different plants in other areas. Scientific names eliminate such ambiguity by providing a single, internationally recognized identifier for each species.
• Comprehensive Coverage
  • Inclusivity of Species: Scientific names cover all known species, including those without widely recognized common names. This ensures that every species can be accurately identified and discussed within the scientific community.
  • Multiple Common Names: Different regions or languages may have multiple common names for the same species, which can complicate communication. Scientific names provide a singular reference point, thus streamlining the process of information exchange.

Common name and its problems

Common names, while widely used, present several issues that complicate plant identification and communication. These problems arise from their variability, lack of precision, and potential for confusion. Here are the main issues associated with common names:

1. Lack of Universality
   • Language-Specific Usage: Common names are often specific to a particular language or region. For instance, the plant Aegle marmelos is known as “wood apple” in English, “sriphal” in Hindi, “bael” in Bengali, and “bilamu” in Telugu. This regional variation means that the same plant can be referred to by different names in different locales, making cross-linguistic communication challenging.
   • Absence for Some Species: Not all plants have widely recognized common names. For example, many newly discovered or less well-known species lack vernacular names, leading to potential gaps in communication and documentation.
2. Lack of Scientific Information
   • No Taxonomic Context: Common names do not convey the taxonomic relationships between plants. In contrast, scientific names provide hierarchical classification—assigning a species to a genus, a genus to a family, and so on. This system, exemplified by Quercus (oak) and Pinus (pine), offers detailed information about the plant’s position in the broader biological classification.
3. Regional Variability
   • Different Names for the Same Plant: The same plant may have multiple common names depending on the region. For example, Rhus vernix is known as “poison sumac,” “poison dogwood,” “poison elder,” and “swamp-sumac” in various places. This variability can create confusion when referring to a specific plant species across different regions.
   • One Name for Multiple Plants: A single common name can refer to different plants. For instance, “oak” can denote Quercus (true oak), Lithocarpus (tanbark oak), Rhus (poison oak), or Grevillea (silk oak). Similarly, “pine” is a general term that can apply to genera such as Pinus, Araucaria, Agathis, or Casuarina.
4. Overlap of Vernacular Names
   • Same Name for Unrelated Plants: Common names can be reused for unrelated species. For example, “cowslip” refers to Caltha palustris in North America but also to Primula veris in the UK. Similarly, “blue bell” can denote Hyacinthoides non-scripta in North America and Campanula rotundiflora in Scotland. This overlap can lead to misidentification and confusion.

Why Scientific names are written in Latin?

Scientific names are universally written in Latin for several compelling reasons, which ensure consistency and precision in plant taxonomy. The adoption of Latin as the standard language for scientific nomenclature is mandated by the International Code of Nomenclature. Here’s why Latin is preferred:

1. Stability and Consistency
   • Dead Language: Latin is classified as a “dead” language, meaning it is no longer spoken in everyday life. Therefore, its meanings and grammatical structures remain unchanged over time. This stability helps avoid confusion that could arise from evolving language use or shifting interpretations in living languages.
   • Fixed Meanings: Because Latin is not subject to the dynamics of modern spoken languages, the meanings of Latin terms are consistent. For instance, “aphylla” translates to “leafless,” and “aquatica” refers to “in water.” Such precision ensures that scientific names retain their intended meaning across different contexts and time periods.
2. Precision in Terminology
   • Exact Descriptions: Latin is highly specific in its terminology, which is crucial for accurately describing plant characteristics. Terms such as “nigra” (black) and “alba” (white) convey exact color descriptions, while “terrestris” indicates plants growing on land and “palustris” denotes those found in marshy environments.
   • Descriptive Epithets: Latin provides a detailed and unambiguous method for naming plants based on their features or habitat. For example, Quercus alba (white oak) uses “alba” to specify the tree’s color, ensuring clear and accurate communication among scientists.
3. Grammatical Structure
   • Consistent Grammar: Latin names follow specific grammatical rules, which help maintain clarity and uniformity. The endings of Latin words can denote gender and other grammatical categories. For example, the suffixes “-um,” “-a,” and “-us” indicate neuter, feminine, and masculine genders respectively. This structured approach helps standardize the formation of scientific names.
   • Gender Agreement: The grammatical rules of Latin require agreement between the genus and species epithets. For instance, Pisum sativum (garden pea) uses “sativum,” a neuter form, consistent with the Latin rules for naming.
4. Compatibility with Modern Alphabets
   • Roman Alphabet: Latin employs the Roman alphabet, which is widely used in many modern languages. This compatibility ensures that scientific names can be easily written and recognized in diverse linguistic contexts. It facilitates the global dissemination of scientific information and makes Latin names accessible across various languages and regions.

The Advantages of Scientific names

Scientific names offer several distinct advantages that enhance clarity and efficiency in biological classification. These benefits are integral to effective communication and accurate identification within the scientific community. The key advantages are as follows:

1. Ease of Reference
   • Simplified Identification: Scientific names provide a standardized reference for each plant or organism, which simplifies communication and documentation. For instance, referring to Campanula by its scientific name is more straightforward than using a lengthy descriptive phrase. This ease of reference facilitates efficient discussion and record-keeping in scientific research and education.
   • Consistent Terminology: Scientific names ensure that the same term is used universally to refer to a specific species, regardless of regional languages or common names. This consistency is crucial for avoiding misunderstandings and errors in scientific contexts.
2. Enhanced Communication
   • Universal Language: Scientific names act as a universal language, allowing scientists and researchers from different linguistic backgrounds to communicate effectively. Similar to how personal names serve as unique identifiers for individuals, scientific names provide a unique identifier for each species, ensuring clear and consistent communication.
   • Standardized Nomenclature: By adhering to standardized naming conventions, scientific names reduce ambiguity and confusion that might arise from the use of regional or vernacular names. For example, the scientific name Quercus robur unambiguously identifies the oak species, whereas common names may vary regionally.
3. Unambiguity and Universality
   • Precise Identification: Scientific names are formulated to be unambiguous. Each name is unique to a particular species or taxonomic group, which eliminates the possibility of confusion that might occur with common names. For instance, the name Homo sapiens clearly identifies modern humans without overlap or ambiguity.
   • Global Application: The use of Latin for scientific names ensures that the nomenclature system is universally applicable. This global standardization is essential for international collaboration and the accurate exchange of scientific information.
4. Avoidance of Descriptive Phrases
   • Concise Communication: Using scientific names eliminates the need for lengthy descriptive phrases when referring to specific plants or organisms. Instead of describing a plant as “a species with blue, elongated, bell-shaped flowers on long stalks,” one can simply use the name Campanula. This efficiency is particularly valuable in scientific writing and conversation.
   • Clarity and Precision: Scientific names provide a clear and precise method for identifying and discussing organisms. This precision is essential for accurate scientific descriptions and classifications, enabling effective research and data analysis.

Laws And Provisions

The International Code of Nomenclature for Algae, Fungi, and Plants (ICN) establishes a comprehensive framework for naming and classifying these organisms. This framework is crucial for maintaining clarity and consistency in botanical nomenclature. The code outlines several key features and principles that guide the naming process.

Salient Features of the Preamble

1. Need for a Universal System
   • Objective: The ICN emphasizes the necessity for a uniform and straightforward nomenclature system applicable globally. This system includes specific terms for different taxonomic ranks and standardized scientific names for taxonomic groups.
   • Function: The purpose of naming is to facilitate reference to taxonomic groups and indicate their rank, rather than to describe their characteristics or historical context.
2. Scope of the Code
   • Organisms Covered: The ICN applies to algae, fungi, and plants. The term ‘organism’ within this context refers specifically to these groups as traditionally studied by botanists, mycologists, and phycologists.
3. Foundational Principles
   • Basis: The Code is founded on several core principles that shape its system of nomenclature. These principles ensure consistency and stability in naming practices.
4. Rules and Recommendations
   • Structure: The ICN divides its provisions into rules, outlined in Articles, and recommendations. These sections are supported by examples to clarify their application.
   • Purpose: Rules aim to standardize nomenclature both retrospectively and prospectively, while recommendations address subsidiary issues to promote uniformity and clarity.
5. Governance and Implementation
   • Regulations: The Code includes provisions for its governance and the application of its rules. This ensures proper management and adherence to the Code.
6. Coverage and Exceptions
   • Inclusion: The Code encompasses all traditionally recognized algae, fungi, and plants, including fossil and non-fossil forms, such as blue-green algae, chytrids, oomycetes, slime molds, and photosynthetic protists. Notably, microsporidia are excluded.
   • Hybrids: Specific provisions for hybrid names are detailed in Appendix ‘I’.
7. Appendices
   • Content: Appendices provide additional information, including conserved and rejected names, suppressed works, and binding decisions, crucial for historical and regulatory reference.
8. Supersession of Previous Editions
   • Update: This edition of the Code replaces all prior editions, reflecting ongoing revisions and updates in botanical nomenclature.

The Six Principles Defining the Code

1. Independence from Other Nomenclatures
   • Principle: Botanical nomenclature operates independently from zoological and bacteriological nomenclature. It applies equally to groups considered algae, fungi, and plants, regardless of their historical treatment.
2. Application of Nomenclature Types
   • Principle: The application of names to taxonomic groups is determined by the use of nomenclature types, which serve as references for correct naming.
3. Priority of Publication
   • Principle: The nomenclature of a taxonomic group is based on the principle of priority, which stipulates that the earliest validly published name takes precedence.
4. Single Correct Name
   • Principle: Each taxonomic group can have only one correct name, which is the earliest name in accordance with the rules, with some specified exceptions.
5. Latin Treatment of Scientific Names
   • Principle: Scientific names are treated as Latin names, irrespective of their origin or derivation, to maintain uniformity.
6. Retroactive Application of Rules
   • Principle: The rules of nomenclature are applied retroactively unless explicitly stated otherwise, ensuring consistency across historical and contemporary names.

Organised Nomenclature History

The history of organized nomenclature in botany reflects the evolution from complex and unwieldy naming systems to a standardized, systematic approach. This development has been crucial for clarity and consistency in plant classification. The key milestones in this evolution are detailed below:

1. Early Descriptive Names
   • Polynomial Names: For many centuries, plants were named using polynomial nomenclature, which involved long, descriptive phrases. These names, such as Salix pumila angustifolia altera for willow by Clusius in 1583, were often cumbersome and difficult to remember. The use of such extensive descriptions created challenges in communication and record-keeping.
2. Introduction of Binomial Nomenclature
   • Casper Bauhin (1623): In the early 17th century, Casper Bauhin introduced the binomial nomenclature system, which simplified plant names to a two-word format: genus and species. His work, Pinax, listed around 6000 plants using this system, although it was not universally adopted at the time. Bauhin’s approach laid the groundwork for future developments but did not make a lasting impact on the botanical community of his era.
3. Formalization by Carolus Linnaeus
   • Early Contributions (1737): Carolus Linnaeus advanced the principles of plant nomenclature with his works Critica Botanica and Fundamenta Botanica, which established foundational rules and regulations for naming plants. His approach was instrumental in formalizing the nomenclature process.
   • Major Publication (1753): In 1753, Linnaeus published Species Plantarum, where he employed binomial nomenclature comprehensively, providing a standardized system for naming plants. This work marked a significant shift towards a more organized and systematic approach to plant classification.
4. Further Refinements
   • A.P. de Candolle (1813): A.P. de Candolle made significant contributions with his work Théorie élémentaire de la botanique, which presented a detailed set of rules for plant nomenclature. His work refined the principles of nomenclature and provided a more structured framework for plant classification.
   • E.G. Steudel (1821): E.G. Steudel published Nomenclator Botanicus, a comprehensive list of Latin names for flowering plants along with their synonyms. This work was influential in Europe and America, with its second edition appearing in 1840 and serving as a key reference for botanists for an extended period.
5. International Efforts
   • Alphonse de Candolle (1867): Alphonse de Candolle, building on his father’s work, circulated Lois de la nomenclature botanique at the 1st International Botanical Congress. This manuscript was a pivotal moment in the formalization of botanical nomenclature, representing the first organized effort to establish uniform naming conventions on an international scale.

Codes of Nomenclature (History till dates)

The evolution of botanical nomenclature has been guided by a series of international codes, each contributing to the refinement and standardization of plant naming practices. These codes reflect the ongoing efforts to maintain consistency and clarity in the naming of plants. Below is a detailed historical account of the major codes of nomenclature:

1. Paris Code (1867)
   • Foundation and Adoption: The first International Botanical Congress, held in Paris, established the Paris Code, also known as the de Candolle rules. This code marked a significant step in formalizing botanical nomenclature.
   • Key Features:
     • Linnaeus’s work was established as the starting point for plant nomenclature.
     • The rule of priority, which dictates that the earliest published name for a taxon is the valid one, was introduced.
     • Author citation became important for validating names, and guidelines for acceptance and rejection were set.
   • Challenges: The adoption of the Kew rule by English botanists led to divergences and deviations from the Paris Code.
2. Rochester Code (1892)
   • Introduction: Dr. N.L. Britton and other botanists convened in Rochester, New York, to develop this code.
   • Key Features:
     • Introduced the concept of nomenclatural types, which are reference specimens used to define taxa.
     • Emphasized strict adherence to the principle of priority.
     • Accepted all binomials resulting from the application of the rule of priority, even in the case of tautonyms (e.g., Malus malus).
3. Vienna Code (1905)
   • Modifications: Held in Vienna, this code modified the Paris Code.
   • Key Features:
     • Established Linnaeus’s Species Plantarum (1753) as the starting point for vascular plant nomenclature.
     • Validated generic names from Linnaeus’s Genera Plantarum (1754).
     • Conserved many old generic names due to their long-standing use.
     • Rejected tautonyms and required Latin diagnoses for new groups.
     • Priority was determined solely by the date of publication.
4. American Code (1907)
   • Revisions: This code did not accept the list of conserved names and the requirement for Latin diagnoses established in previous codes.
5. 5th International Botanical Congress (1930)
   • Developments: This congress led to the creation of a truly international code.
   • Key Features:
     • Reconciled differences between the Vienna and American codes.
     • Accepted nomenclatural types and rejected tautonyms.
     • Mandated Latin diagnoses for new taxa starting January 1, 1932.
     • Approved conserved names.
6. 6th International Botanical Congress (1935)
   • Changes: From January 1, 1935, new taxa were required to have Latin diagnoses to be considered validly published.
   • Key Features:
     • Efforts to create a list of conserved names were unsuccessful.
7. 7th International Botanical Congress (1950)
   • Clarifications: Introduced definitions related to nomenclatural types.
8. 8th International Botanical Congress (1954)
   • Focus: Emphasized nomenclatural types, but the rule requiring Latin diagnoses faced criticism.
9. 9th International Botanical Congress (1959)
   • Special Committee: Appointed to study the conservation of family names.
10. 10th International Botanical Congress (1964)
    • Adoptions:
      • Adopted the International Code of Botanical Nomenclature (ICBN).
      • Settled nomenclature rules and provisions.
      • Established A.L. de Jussieu’s Genera Plantarum (1789) as the starting point for family names.
      • Provided a ready reference for family names with type genera.
11. 11th International Botanical Congress (1969)
    • Issues Addressed: Addressed tautonymous designations, superfluous names, and rules for hybrids.
12. 12th International Botanical Congress (1975)
    • Revisions:
      • Numbered individual paragraphs in a decimal system and rearranged some sections.
      • Eliminated organ-genera for fossil plants.
      • Extended the principle of automatic typification based on priority.
      • Clarified that the code does not apply to bacterial names.
13. 13th International Botanical Congress (1981)
    • Provisions:
      • Accepted the conservation of species names but did not include it in the code.
      • Maintained provisions for hybrids and recognized autonyms as validly published.
14. 14th International Botanical Congress (1988)
    • Language Changes: The code text was published only in English, replacing the previous multilingual format.
    • Requirements: Mandated the inclusion of the type’s place of preservation starting January 1, 1990.
15. 15th International Botanical Congress (1993)
    • Updates: Continued the evolution of nomenclature rules and addressed various issues related to plant naming.
16. 16th International Botanical Congress (1999)
    • Further Developments: Continued refinement of nomenclature standards.
17. 17th International Botanical Congress (2005)
    • Revisions: Continued updates and adjustments to nomenclature practices.
18. 18th International Botanical Congress (2011)
    • Renaming and Updates:
      • Renamed the code to the International Code of Nomenclature for algae, fungi, and plants (ICN).
      • Allowed English diagnoses and electronic publication starting January 1, 2012.
19. 19th International Botanical Congress (2017)
    • Current Developments: Addressed ongoing issues and updates in the field of botanical nomenclature.

International Code of Nomenclature of algae, fungi and plants (ICN)

[Formerly International Code of Botanical Nomenclature (ICBN)]

The International Code of Nomenclature of Algae, Fungi, and Plants (ICN), formerly known as the International Code of Botanical Nomenclature (ICBN), is the authoritative framework for naming organisms traditionally classified as algae, fungi, and plants. This includes both fossil and non-fossil groups, such as blue-green algae, chytrids, oomycetes, slime molds, and photosynthetic protists, along with their taxonomically related non-photosynthetic counterparts. The primary objective of the ICN is to ensure that each taxonomic entity is assigned a single, universally accepted name.

Historical Evolution

• ICBN to ICN Transition: Initially adopted by the 10th International Botanical Congress in Edinburgh in 1964, the ICBN was renamed the ICN during the 18th International Botanical Congress held in Melbourne in 2011. This renaming reflected an expansion of the code’s scope beyond traditional botanical nomenclature to include fungi and algae more comprehensively.
• Current Version: The most recent version of the ICN, known as the Shenzhen Code, was established at the 19th International Botanical Congress in Shenzhen, China, in July 2017. This version became effective from June 26, 2018.

Structure of the ICN

The Code is divided into 3 divisions –

1. Principles
   • Core Foundation: The Principles are the fundamental tenets that underpin the nomenclatural system. They are designed to organize historical names and guide future nomenclature. Names that contravene these principles are deemed invalid.
   • Function: The Principles ensure a stable and universally applicable naming system, providing a foundation for consistency in taxonomy.
2. Rules and Recommendations
   • Rules: The ICN consists of 62 main rules (Articles) which must be adhered to. These rules establish the guidelines for the correct application of names and are essential for maintaining order in nomenclature.
   • Recommendations: While recommendations are intended to guide and standardize practices, names contrary to these recommendations are not invalidated. They aim to enhance uniformity and clarity in the naming process.
3. Provisions for Governance
   • Administrative Framework: This section includes provisions for the administration and interpretation of the code, ensuring that its application remains consistent and effective across different contexts.

Appendices

In addition, the code includes the following appendices –

• Appendix (i): Provides rules related to the naming of hybrids, including guidelines on how hybrid names should be formed and used.
• Appendix (ii) and (iii): List conserved names for families of algae, fungi, and pteridophytes, and for bryophytes and spermatophytes, respectively. These appendices help preserve long-established names and avoid unnecessary changes.
• Appendix (iv) and (v): Include lists of conserved and rejected generic and specific names. These lists help to clarify which names are accepted and which are to be disregarded.
• Appendix (vi): Contains names and combinations deemed rejected under Article 56. This ensures that certain names are not used, providing clarity and consistency in nomenclature.
• Appendix (vii): Lists publications that are not considered validly published according to the code, thus ensuring that only recognized sources contribute to valid nomenclature.

The ICN serves as a crucial tool for taxonomists worldwide, ensuring that names are assigned and used in a consistent manner, thus facilitating clear communication and collaboration in the scientific community.

Principles Of ICN (Icbn)

The International Code of Nomenclature of Algae, Fungi, and Plants (ICN) is grounded in a set of principles that guide the formal naming and classification of taxonomic groups. These principles ensure a consistent and universally applicable framework for naming, thus facilitating clear communication within the scientific community. The following principles are foundational to the ICN:

1. Principle I: Independence from Other Nomenclatures
   • Description: Botanical nomenclature operates independently of zoological and bacteriological nomenclature. This principle establishes that the naming conventions for plants, including algae and fungi, are separate from those used for animals and bacteria.
   • Function: Ensures that the rules and standards applied to plant nomenclature are not influenced by or conflated with those of other biological disciplines.
2. Principle II: Nomenclatural Types
   • Description: The application of names to taxonomic groups is determined through nomenclatural types. This principle underscores that each name is linked to a specific type specimen or illustration that serves as the reference point for that name.
   • Function: Provides a stable and objective basis for identifying and classifying taxa by associating names with designated type specimens.
3. Principle III: Priority of Publication
   • Description: The nomenclature of a taxonomic group is based on the principle of priority of publication. This means that the first validly published name for a taxon takes precedence over subsequent names.
   • Function: Ensures consistency and historical continuity in naming by prioritizing earlier published names and thus avoiding duplication or confusion.
4. Principle IV: Single Correct Name
   • Description: Each taxonomic group with a specific circumscription, position, and rank is assigned only one correct name. This name is the earliest that complies with the rules, except in cases where exceptions are specified.
   • Function: Promotes clarity and uniformity by ensuring that each taxon has a single, accepted name, thereby minimizing ambiguity and redundancy.
5. Principle V: Latin Names
   • Description: Scientific names of taxonomic groups are treated as Latin names, regardless of their actual linguistic derivation. This principle mandates that all scientific names conform to Latin grammatical rules and conventions.
   • Function: Maintains consistency in the presentation and usage of scientific names by standardizing them in Latin, which is the traditional language for taxonomic classification.
6. Principle VI: Retroactive Application
   • Description: The rules of nomenclature are applied retroactively unless explicitly stated otherwise. This means that the rules govern names and classifications that have been established in the past.
   • Function: Ensures that the nomenclature system remains applicable to historical names and classifications, thereby providing a coherent and comprehensive framework for both current and historical taxa.

These principles collectively underpin the ICN, guiding the scientific community in the consistent and accurate naming of algae, fungi, and plants. They ensure that nomenclature practices remain orderly, transparent, and universally applicable across different regions and historical contexts.

Rules Of Nomenclature

The rules of nomenclature under the International Code of Nomenclature of Algae, Fungi, and Plants (ICN) provide a structured framework for naming and classifying plant taxa. These rules ensure that scientific names are unique, stable, and universally accepted. The following are key rules that govern botanical nomenclature:

1. Principle of Priority (Rule of Priority)
   • Description: The principle of priority dictates that the earliest validly published name for a taxon is the correct name. This rule establishes precedence for names based on their initial publication.
   • Function: Ensures consistency and historical continuity by favoring the earliest published names and avoiding redundancy.
2. Nomenclatural Type
   • Description: Each taxonomic name is associated with a nomenclatural type, which is a specific specimen or illustration that serves as the reference point for that name.
   • Function: Provides a stable basis for identifying and classifying taxa by linking names to designated type specimens, thereby reducing ambiguity.
3. Rank of Taxa
   • Description: The rules specify how names are assigned to different taxonomic ranks, such as species, genus, and family. Each rank has its own set of naming conventions.
   • Function: Ensures clarity and consistency in the classification of taxa across different levels of the taxonomic hierarchy.
4. Names of Taxa
   • Description: The rules stipulate how names for taxa should be formed and used. This includes guidelines on the formation of names and their Latinization.
   • Function: Maintains uniformity and clarity in the naming process by adhering to standardized conventions.
5. Effective and Valid Publication
   • Description: A name must be effectively published to be considered valid. This involves adhering to specific requirements, such as providing a description and making the publication accessible.
   • Function: Ensures that names are formally and publicly recognized, thereby maintaining the integrity of the nomenclature system.
6. Retention of Specific and Infra-specific Epithets
   • Description: Specific (species) and infra-specific (subspecies, varieties) epithets are retained based on rules that govern their usage and modifications.
   • Function: Provides stability in the naming of taxa by maintaining consistency in the application of specific and infra-specific names.
7. Rejection of Names
   • Description: The rules outline conditions under which names may be rejected, such as those that are deemed invalid or inappropriate.
   • Function: Helps maintain clarity and avoid confusion by eliminating names that do not meet the standards set by the nomenclature system.
8. Splitting of a Genus
   • Description: When a genus is divided into multiple genera, the rules specify how names should be handled and what criteria should be used for the new genera.
   • Function: Ensures that the splitting of genera is conducted in a systematic manner, preserving nomenclatural stability.
9. Synonym and Basionym
   • Description: Synonyms are different names that refer to the same taxon, while a basionym is the original name upon which a new name is based.
   • Function: Facilitates the identification of name changes and historical references, aiding in the organization and retrieval of taxonomic information.
10. Author Citation
    • Description: The rules specify how authors’ names should be cited in connection with the names of taxa, including the format and placement of citations.
    • Function: Provides proper attribution and recognition to the individuals who originally described the taxa.
11. Names of Hybrids
    • Description: Special rules apply to the naming of hybrids, including how hybrid names are formed and published.
    • Function: Addresses the unique aspects of hybrid taxa, ensuring that their names are created and used consistently.
12. Names of Cultivated Plants
    • Description: The nomenclature for cultivated plants is governed by specific rules that address the formation and use of names in agriculture, horticulture, and forestry.
    • Function: Ensures that names for cultivated plants adhere to established conventions while accommodating their unique characteristics.

Rule 1 – Principle of Priority (Rule of Priority)

The Principle of Priority, as outlined in the International Code of Nomenclature of Algae, Fungi, and Plants (ICN), plays a crucial role in ensuring the stability and consistency of botanical nomenclature. This principle dictates that the correct name for a taxonomic group is determined by the earliest validly published name. Here is a detailed examination of this principle:

Core Concepts of the Principle of Priority

1. Single Correct Name
   • Definition: Each taxonomic group, regardless of its rank, is assigned only one correct name, based on priority of publication.
   • Function: This ensures that each group is known by a single, stable name, avoiding confusion and promoting clarity in scientific communication.
2. Selection of Names
   • Process: If multiple legitimate names are available for a taxon, the earliest validly published name is selected as the correct name.
   • Application: This rule applies to all ranks from family down to species. It emphasizes the importance of historical precedence in naming conventions.
3. Validity of Names
   • Requirement: A name must be validly published to be considered under this code. Valid publication includes specific criteria such as accessibility and detailed description.
   • Purpose: This rule prevents the use of names that have not been formally introduced to the scientific community, ensuring that only recognized names are used.
4. Handling Multiple Names
   • Procedure: When a taxonomist identifies that a taxon includes types from several previously published names, the oldest legitimate name is selected. All other names become synonyms.
   • Objective: This approach simplifies nomenclature by consolidating synonyms under the earliest name, thus avoiding redundancy.
5. Types and Synonyms
   • Distinction: Each taxonomic synonym is linked to a separate type. This distinction helps in tracing the original descriptions and contexts of different names.
   • Significance: Understanding types and synonyms aids in clarifying historical changes in taxonomy and preserving the integrity of scientific names.
6. Author Citation in New Combinations
   • Rule: When a species name is transferred from one genus to another, the original author’s name is placed in parentheses, followed by the author of the new combination.
   • Function: This citation method acknowledges both the original author and the person responsible for the new combination, maintaining historical accuracy.
7. Rejection of Homonyms
   • Policy: Homonyms, which are names that are identical but apply to different taxa, are considered illegitimate and cannot be used as correct names.
   • Purpose: This rule prevents the confusion that could arise from using identical names for different taxa, thereby ensuring clarity in botanical nomenclature.

Limitations of the Principle of Priority

1. Historical Cut-off Dates
   • Exception: For plants, the earliest date of validity is set as May 1, 1753, based on Linnaeus’s “Species Plantarum.” This does not apply to fungi, some algae, or certain mosses.
   • Implication: This cut-off ensures that names published before this date are considered in the priority system, while accommodating groups with different historical contexts.
2. Application to Taxonomic Ranks
   • Scope: The principle of priority is applicable only up to the family rank. For ranks above family, other rules and principles govern nomenclature.
   • Reason: This limitation ensures that priority is used appropriately within the bounds of the taxonomic hierarchy, where it is most effective.
3. Rank-Specific Naming
   • Consideration: When choosing a correct name, names available at the specific rank must be considered. If no suitable name is available, epithets from other ranks may be used.
   • Purpose: This approach ensures that names are appropriate for the rank in question, enhancing the accuracy and relevance of taxonomic names.

Rule 2 – Nomenclatural Type/ Type Method/ Typification

Nomenclatural types are fundamental elements in botanical taxonomy that establish the application of names for taxa, including families, genera, and species. The principle of typification, as outlined in Article 7 of the International Code of Nomenclature for algae, fungi, and plants (ICN), ensures that each taxon has a definitive reference point. This process provides a standardized method for naming and classifying taxa based on a specific type specimen or illustration. Below is an in-depth explanation of the types and methods used in typification.

Core Concepts of Nomenclatural Types

The different kinds of ‘type’ or ‘elements’ designated by ICN (ICBN) are as follows:-

1. Holotype
   • Definition: A holotype is a single specimen or illustration designated by the author as the nomenclatural type to which the name of the taxon is permanently attached.
   • Function: It serves as the primary reference for the taxon’s name, providing a concrete example of the taxon as described in the original publication.
2. Isotype
   • Definition: An isotype is a duplicate of the holotype, collected from the same location and at the same time by the same person. It often bears the same collection number but is differentiated by letters (a, b, c, etc.).
   • Function: Isotypes provide additional reference specimens for verification and comparison, ensuring that the holotype’s characteristics can be corroborated.
3. Syntype
   • Definition: Syntypes are two or more specimens cited by the author when no holotype was designated, or any one of these original specimens designated as types.
   • Function: In the absence of a holotype, syntypes collectively represent the original material of the taxon. A duplicate of a syntype is called an isosyntype.
4. Paratype
   • Definition: A paratype is a specimen cited in the protologue that is neither a holotype nor an isotype nor one of the syntypes but is from the same collection.
   • Function: Paratypes offer supplementary material that helps in understanding the variability and distribution of the taxon.
5. Lectotype
   • Definition: A lectotype is a specimen selected from the original material when no holotype was designated or when the holotype is missing or destroyed. It is chosen from among isotypes, syntypes, or paratypes.
   • Function: Lectotypes serve as the new type specimen when the original designation is inadequate or unavailable.
6. Neotype
   • Definition: A neotype is selected to replace a holotype when all original material is missing. It provides a new reference point for the taxon.
   • Function: Neotypes ensure that a taxon still has a valid type reference when the original material is lost or inaccessible.
7. Topotype
   • Definition: A topotype is a specimen collected from the same locality as the holotype.
   • Function: Topotypes offer additional references from the original geographic location, enhancing the understanding of the taxon’s distribution.
8. Epitype
   • Definition: An epitype is a specimen or illustration chosen to serve as an interpretative type when the holotype, lectotype, or neotype is ambiguous or inadequate for precise identification.
   • Function: Epitypes clarify the application of a name when the original types are not sufficiently informative.
9. Merotype
   • Definition: A merotype is a fragment of the original holotype that has been divided into two or more pieces.
   • Function: It maintains the original reference material while facilitating the study of different parts of the holotype.
10. Schizotype
    • Definition: Any fragment of a type specimen is termed a schizotype.
    • Function: Schizotypes help preserve and distribute type material for broader research use.
11. Clastotype
    • Definition: The portion of the same clone used as a type.
    • Function: Clastotypes ensure that clones from the same original material are referenced in taxonomic studies.
12. Paralectotype
    • Definition: Paralectotypes are the specimens left after the selection of a lectotype from among the syntypes.
    • Function: They provide additional context and reference points after a lectotype has been designated.
13. Synonymotype
    • Definition: A synonymotype is a specimen cited by the author as identical with a newly described taxon.
    • Function: Synonymotypes help in understanding the relationship between newly described taxa and previously established ones.

Special Considerations in Typification

• Ex-Type: Refers to living isolates obtained from a culture preserved in a metabolically inactive state, such as ex-type or ex-holotype.
• Autonym: When an infraspecific variant is recognized within a species, it establishes two infraspecific taxa, one of which shares the same epithet as the species (e.g., Acacia nilotica ssp. nilotica). This is known as an autonym, and the specimen is termed an autotype.

Publication and Typification Rules

• Post-1958: For new taxa published from January 1, 1958, onwards, the type of the name must be indicated.
• Post-1990: Names of new taxa published from January 1, 1990, must include the terms ‘typus’ or ‘holotypus’ or their abbreviations.
• Post-2001: Lectotypification or neotypification must be indicated using ‘lectotypus’ or ‘neotypus’ from January 1, 2001.
• Post-2007: Names published from January 1, 2007, require a specimen as a type, with exceptions for microscopic algae or microfungi where illustrations may be used.

Rule 3 – Ranks Of Taxa

In taxonomic classification, the concept of ranks organizes living organisms into hierarchical levels, reflecting their evolutionary relationships and similarities. This system, rooted in the Linnaean framework, provides a structured approach to classifying and naming organisms. The following outlines the principal ranks and their usage in taxonomic nomenclature.

Principal Ranks in Taxonomy

1. Kingdom (Regnum)
   • Definition: The highest taxonomic rank, encompassing the broadest classification of organisms.
   • Function: Represents major groups such as Animalia, Plantae, and Fungi. This rank is foundational in categorizing all living organisms into broad domains of life.
2. Division or Phylum (Divisio, Phylum)
   • Definition: A major taxonomic rank below Kingdom and above Class.
   • Function: Groups organisms based on significant structural and developmental features. For example, in plants, the division Angiosperms (flowering plants) is categorized into various classes based on reproductive and anatomical characteristics.
3. Class (Classis)
   • Definition: A rank below Division or Phylum and above Order.
   • Function: Organizes taxa based on more specific characteristics shared among organisms. For instance, the class Mammalia includes all mammals, characterized by features such as hair and mammary glands.
4. Order (Ordo)
   • Definition: A rank below Class and above Family.
   • Function: Groups organisms with even closer similarities. For example, the order Carnivora includes all carnivorous mammals like lions and bears.
5. Family (Familia)
   • Definition: A rank below Order and above Genus.
   • Function: Collects genera that share a common evolutionary ancestor. For instance, the family Felidae includes all cats, both domestic and wild.
6. Genus (Genus)
   • Definition: A rank below Family and above Species.
   • Function: Groups species that are closely related and resemble each other. For example, the genus Homo includes humans and their close ancestors.
7. Species (Species)
   • Definition: The most specific rank, below Genus.
   • Function: Identifies individual organisms that can interbreed and produce fertile offspring. For instance, Homo sapiens is the species name for modern humans.

Infra-Specific Ranks

1. Subspecies (Subspecies)
   • Definition: A rank below Species, used to denote populations with distinct morphological or genetic differences.
   • Function: Represents variations within a species that are geographically or ecologically distinct, such as different subspecies of a single species.
2. Variety (Varietas)
   • Definition: A rank below Subspecies, used to classify plants or animals showing minor but consistent differences.
   • Function: Identifies natural variations that are less distinct than subspecies but still recognizable, like variations in flower color.
3. Subvariety (Subvarietas)
   • Definition: A rank below Variety.
   • Function: Further subdivides varieties into more specific categories, reflecting even finer differences.
4. Form (Forma)
   • Definition: A rank below Subvariety.
   • Function: Designates minor variations within a variety or subspecies, often based on specific traits such as leaf shape or flower size.
5. Subform (Subforma)
   • Definition: A rank below Form.
   • Function: Provides a classification for even more detailed variations, often reflecting specific morphologies or anomalies.
6. Forma Specialis (Special Form)
   • Definition: An additional rank used specifically in Fungi.
   • Function: Differentiates fungal taxa based on their host relationships or other specific characteristics.

Additional Ranks and Prefixes

1. Tribe (Tribus)
   • Definition: An optional rank between Family and Genus.
   • Function: Used primarily in large families to organize genera into more manageable groups.
2. Supra- and Sub- Prefixes
   • Definition: Prefixes like ‘super-’ and ‘infra-’ are used to denote ranks above or below standard ranks.
   • Function: These prefixes help in specifying ranks that are not strictly defined within the primary hierarchy, such as superfamily or infraclass.
3. Notho- Prefix
   • Definition: Used for hybrid taxa.
   • Function: Indicates hybrid origins within a taxonomic classification, such as nothospecies.
4. Super- and Infra- Prefixes
   • Definition: Used to denote ranks above or below a given level.
   • Function: Enhances clarity in hierarchical classification, such as superorder or infraorder.

Rule 4 – Names of Taxa

The nomenclature of taxa provides a systematic method for classifying and naming organisms based on their rank within the taxonomic hierarchy. This system ensures clarity and consistency in scientific communication. The following details outline how the names of taxa are determined, including the use of specific endings and the structure of names at various taxonomic levels.

Endings of Taxa Names

Taxonomic names are often associated with specific suffixes that indicate their rank within the hierarchy. The rules for these suffixes help categorize taxa into their respective levels:

1. Kingdom
   • Ending: bionta
   • Example: Plantae (Kingdom of plants).
2. Division (Phylum)
   • Ending: phyta
   • Example: Magnoliophyta (Division of flowering plants).
3. Sub-Division
   • Ending: phytina
   • Example: Not commonly used but applicable within specific classifications.
4. Class
   • Ending: opsida
   • Example: Magnoliopsida (Class of dicotyledonous plants).
5. Subclass
   • Ending: opsidae or -idea
   • Example: Lamiidae (Subclass of the order Lamiales).
6. Order
   • Ending: ales
   • Example: Rosales (Order including roses and related plants).
7. Suborder
   • Ending: ineae
   • Example: Fagales (Suborder within the order Rosales).
8. Family
   • Ending: aceae
   • Example: Rosaceae (Family including roses).
9. Subfamily
   • Ending: oideae
   • Example: Maloideae (Subfamily within the Rosaceae family).
10. Tribe
    • Ending: eae
    • Example: Astereae (Tribe within the Asteraceae family).
11. Subtribe
    • Ending: inae
    • Example: Helianthinae (Subtribe within the tribe Astereae).

Traditional Family Names

While the above rules are generally followed, some traditional family names in angiosperms do not conform to these suffixes but are still considered valid. These include:

1. Cruciferae – Now known as Brassicaceae (Type genus: Brassica).
2. Guttiferae – Now known as Clusiaceae (Type genus: Clusia).
3. Leguminosae – Now known as Fabaceae (Type genus: Faba).
4. Umbelliferae – Now known as Apiaceae (Type genus: Apium).
5. Compositae – Now known as Asteraceae (Type genus: Aster).
6. Labiatae – Now known as Lamiaceae (Type genus: Lamium).
7. Palmae – Now known as Arecaceae (Type genus: Areca).
8. Graminae – Now known as Poaceae (Type genus: Poa).

Generic and Specific Names

1. Generic Name
   • Form: A singular noun that may be masculine, feminine, or neuter.
   • Endings:
     • Masculine: -us, -pogon
     • Feminine: -a, -is
     • Neuter: -um
   • Function: Indicates the genus of the organism. The first letter is always capitalized.
2. Specific Epithet
   • Form: A binomial, where the genus is followed by a specific epithet.
   • Example: Homo sapiens (where Homo is the genus and sapiens is the specific epithet).
   • Rules: Specific epithets should begin with a lowercase letter. They can be derived from names, places, characteristics, or inapposition nouns.

Infraspecific Ranks

1. Subspecies (Trinomial)
   • Structure: Genus + species + subspecific epithet.
   • Example: Angelica archangelica ssp. himalaica.
2. Variety (Quadrinomial)
   • Structure: Genus + species + subspecific epithet + varietal epithet.
   • Example: Bupleurum falcatum ssp. eufalcatum var. hoffmeisteri.
3. Forma (Forma)
   • Structure: Genus + species + forma.
   • Example: Prunus cornuta forma villosa.
4. Polynomial Names
   • Structure: Can include multiple infraspecific ranks.
   • Example: Saxifera aizoon var. aizon subvar. brevifolia f. multicaulis subf. surculosa.

Rule 5 – Effective And Valid Publication

In botanical and taxonomic nomenclature, the concepts of effective and valid publication are critical for ensuring that scientific names are recognized and accepted within the scientific community. Effective publication refers to the dissemination of a name in a manner that makes it accessible and permanent, while valid publication requires adherence to specific rules and criteria established by taxonomic codes. Here is an in-depth look at both concepts:

Criteria for Effective Publication

1. Medium of Publication
   • Requirement: The name must be published in a printed, permanent, and readily accessible form.
   • Acceptable Forms: Books, scientific journals, or other printed media.
   • Unacceptable Forms: Local newspapers, magazines, handwritten manuscripts, or any ephemeral publications.
2. Description Requirement
   • Requirement: The new name must be accompanied by a description of the taxon or a reference to a previously and effectively published description.
   • Purpose: Ensures that the taxon is adequately described for identification and classification purposes.
3. Latin Diagnosis
   • Requirement: A new taxon’s name must include a Latin diagnosis or a reference to a previously and effectively published Latin diagnosis.
   • Purpose: Latin diagnoses provide standardized and precise descriptions critical for taxonomic clarity.
4. Rank Indication
   • Requirement: For names published after January 1, 1953, the rank of the taxon must be clearly indicated.
   • Purpose: Clarifies the taxonomic level at which the name applies.
5. Nomenclature Type
   • Requirement: Publications on or after January 1, 1953, for new taxa of family rank or below must include a nomenclature type.
   • Purpose: Establishes a reference point for the name and ensures consistent application.
6. Holotype Information
   • Requirement: Since January 1, 1958, a holotype must include information on where it is kept.
   • Purpose: Provides a specific location for the type specimen to facilitate access and verification.
7. Type Indication
   • Requirement: For genera or below, published on or after January 1, 1990, the type must be indicated using terms like “typus,” “holotypus,” or their abbreviations.
   • Purpose: Ensures that the type specimen is clearly identified and referenced.
8. Intention to Publish
   • Requirement: The intention to publish new taxa must be explicitly stated by the author.
   • Purpose: Clarifies the author’s intent and establishes the context of the publication.

Important Considerations for Publication

1. Handwritten Material
   • Effective Before 1953: Handwritten material reproduced by mechanical or graphic processes, such as lithography or offset printing, is considered effective if published before January 1, 1953.
2. Fossil Plants
   • Requirement: For new taxa of fossil plants published on or after January 1, 1996, a Latin or English description is required, or a reference to such a description.
3. Electronic Material
   • Effective from 2012: Electronic publications in Portable Document Format (PDF) with an International Standard Serial Number (ISSN) or an International Standard Book Number (ISBN) are considered effective.
4. Fungi Names
   • Single Correct Name: From January 1, 2012, only one correct name applies to all fungi, aligning with other taxonomic groups.
   • Identifier Requirement: Since January 1, 2013, new fungal names must include an identifier issued by a recognized repository.

Legitimacy of Names

• Legitimate Name
  • Definition: A name that is validly published and adheres to all taxonomic rules.
  • Implication: Such names are accepted and used within the scientific community.
• Illegitimate Name
  • Definition: A validly published name that contravenes one or more rules of the taxonomic code.
  • Examples of Illegitimate Names:
    • Synonyms: Different names for the same taxon, which may be nomenclatural (based on the same type) or taxonomic (based on different types but considered the same taxon).
    • Homonyms: Names that are spelled exactly like another validly published name at the same rank but are based on different types.
    • Tautonyms: Binomial names where the specific epithet exactly repeats the generic name, e.g., Malus malus.

Rule 6 – Author Citation

In botanical nomenclature, proper citation of authors is crucial for the accurate identification and validation of plant taxa. According to Articles 46-50 of the International Code of Nomenclature (ICN), the citation of an author’s name provides critical information about the history and legitimacy of a taxon’s name. This article outlines the principles and practices for citing authors in taxonomic publications.

Principles of Author Citation

1. Single Author Citation
   • Requirement: When a taxon is described or validly published by a single author, that author’s name must follow the taxon’s name.
   • Example: Solanum nigrum L. (L. stands for Carolus Linnaeus, who first validly published this species.)
2. Multiple Author Citation
   • Requirement: When a taxon is published by two or more authors, their names are linked using “et” (and).
   • Example: Delphinium viscosum Hook.f. et Thomson (Hook.f. and Thomson are the authors who jointly published the taxon.)
3. Double Citation
   • Requirement: For taxa that have undergone changes in rank or position but retain their original name, the original author’s name is cited in parentheses, followed by the author who made the change.
   • Example: Cynodon dactylon (Linn.) Pers. (Linn. is the original author, and Pers. is the author who made the change. The basionym is Panicum dactylon Linn.)
4. Ex Author Citation
   • Requirement: When a taxon’s name is proposed by one author but validly published by another, the names are linked using “ex” (out of).
   • Example: Gossypium tomentosum Nutt. ex Seem. (Nutt. proposed the name, and Seem. validly published it.)
5. In Author Citation
   • Requirement: When a new species or name is published by one author within the work of another author, the citation is linked using “in” (in).
   • Example: Carex kashmirensis Clarke in Hook.f. (Clarke published the species in Hooker’s work.)
6. Emendation Citation
   • Requirement: When an author revises a taxon’s description or circumscription without changing the type, the citation uses “emend.” (emendation).
   • Example: Phyllanthus Linn. emend. Mull. (Mull. made amendments to Linnaeus’s original description.)
7. Prestarting Point Author
   • Requirement: Square brackets are used to indicate an author who published a name before the starting point for botanical nomenclature.
   • Example: Lupinus [Tourne] L. (Tournefort published Lupinus before Linnaeus’s 1753 starting point.)
8. Infraspecific Taxa
   • Requirement: For infraspecific taxa, the citation must include the author for the taxon at the rank in question, not the rank below it.
   • Example: Rosa gallica L. var. gallica, (The author L. is cited for the variety at the same rank, not lower.)

Author Abbreviations

The names of authors are commonly abbreviated to simplify citations. Here are some examples of author abbreviations:

• L. – Carolus Linnaeus
• Benth. – George Bentham
• Hook. – William Hooker
• Hook.f. – Sir Joseph Dalton Hooker (son of William Hooker)
• R.Br. – Robert Brown
• Lam. – Jean-Baptiste Lamarck
• DC. – Augustin Pyrame de Candolle
• Wall. – Nathaniel Wallich
• A.DC. – Alphonse de Candolle
• Scop. – Giovanni Antonio Scopoli
• Pers. – Christian Hendrik Persoon

Rule 7 – Rejection of name

In botanical nomenclature, the rejection of a taxonomic name is a formal process governed by the International Code of Nomenclature (ICN). This process ensures that names used in the scientific community are valid, unambiguous, and consistent with established rules. Below are the key reasons and criteria for the rejection of taxonomic names:

Criteria for Rejection

1. Ineffective Publication
   • Description: A name may be rejected if it is not effectively published. This includes names published in formats that are not readily accessible or permanent, such as in unpublished manuscripts or local newspapers. Additionally, names lacking essential components like typification or a Latin diagnosis are also rejected.
   • Details: Effective publication requires that the name is distributed in a printed, permanent, and accessible form, accompanied by a description or reference to a description of the taxon.
2. Nomen Nudum (Nom. Nud.)
   • Description: Names published without any descriptive content are classified as nomen nudum. These names are considered invalid and are rejected until they are accompanied by a proper description.
   • Details: A nomen nudum lacks the necessary diagnostic information needed for valid publication, thus failing to meet the criteria set by the ICN.
3. Tautonym
   • Description: Tautonyms are names in which the specific epithet is an exact repetition of the generic name. Such names are rejected under the ICN rules.
   • Details: For example, Malus malus is a tautonym and is not permitted in botanical nomenclature.
4. Later Homonym
   • Description: If two different taxa are assigned the same name, the later name (later homonym) is rejected, even if the earlier name (earlier homonym) is illegitimate.
   • Details: This rule ensures that each taxon has a unique name to avoid confusion. The earlier name retains precedence over the later homonym.
5. Later Isonym
   • Description: When a name is independently published by different authors at different times based on the same type, only the earliest of these names (isonyms) is considered valid.
   • Details: Later isonyms are disregarded in favor of the original valid publication to maintain clarity in nomenclature.
6. Nomen Superfluum (Nom. Superfl.)
   • Description: A name is deemed superfluous if it is given to a taxon that already has an existing valid name. Such names are rejected.
   • Details: The principle of priority means that a name should not be introduced if a valid name for the taxon already exists.
7. Nomen Ambiguum (Nom. Ambig.)
   • Description: A name is rejected if it is used ambiguously by different authors, leading to persistent confusion and errors.
   • Details: Ambiguity in a name’s application undermines its reliability and validity in scientific discourse.
8. Nomen Confusum (Nom. Confus.)
   • Description: Names based on a type with conflicting elements, making it difficult to establish a clear lectotype, are rejected.
   • Details: A nomen confusum arises when the type material is inconsistent, complicating taxonomic clarity.
9. Nomen Dubium (Nom. Dub.)
   • Description: Names of uncertain application due to insufficient information to determine the taxon are classified as nomen dubium and are rejected.
   • Details: A nomen dubium is used when the taxon cannot be confidently identified or linked to a specific entity.
10. Name Based on Monstrosity
    • Description: Names derived from atypical, abnormal, or monstrous forms are rejected.
    • Details: Monstrosities are aberrations and do not represent typical taxa, making such names invalid for formal classification.

Rule 8 – Names of Hybrids

In botanical taxonomy, hybrids represent a significant category of taxa that result from the crossbreeding of different species or genera. The International Code of Nomenclature (ICN) provides specific guidelines for naming these hybrids to ensure clarity and consistency. Below is an outline of the conventions used for naming hybrids:

General Principles for Hybrid Names

1. Indication of Hybridity
   • Description: Hybridity is indicated using a multiplication sign (×) or by adding the prefix ‘notho’ to the rank term. The principal ranks for hybrids are nothogenus and nothospecies.
   • Details: For example, the hybrid between Salix aurita and Salix caprea can be denoted as Salix aurita × Salix caprea. The multiplication sign (×) is used to represent the hybrid status.
2. Binary Names for Interspecific Hybrids
   • Description: Interspecific hybrids, or nothospecies, are given a binary name where the multiplication sign is placed before the specific epithet.
   • Example: Salix × capreola denotes a hybrid between Salix aurita and Salix caprea.
3. Naming Variants of Interspecific Hybrids
   • Description: Variants of interspecific hybrids are designated as nothosubspecies or nothovarieties. These names follow the pattern of the parent nothospecies name, with additional descriptors for the variant.
   • Example: Salix rubens nothovar. basfordiana.
4. Names of Intergeneric Hybrids
   • Description: For intergeneric hybrids, the name is formed using parts of the parental genera. The cross sign is placed before the generic name of the hybrid.
   • Example: ×Triticosecale is an intergeneric hybrid between Triticum and Secale.
5. Nothogeneric Names for Complex Hybrids
   • Description: For hybrids involving four or more genera, a nothogeneric name is formed by combining a person’s name with the suffix -ara.
   • Example: ×Potinara represents a hybrid involving Brassavola, Cattleya, Laelia, and Sophronitis.
6. Grafts Between Species
   • Description: Grafts, or the physical joining of two plant species, are indicated by a plus sign between the grafted species.
   • Example: Rosa webbiana + Rosa floribunda represents a graft between these two species.

Detailed Explanations

• Hybridity Indicators:
  • Multiplication Sign (×): Used to denote hybrid status, both in interspecific and intergeneric hybrids.
  • Prefix ‘Notho’: Applied to rank terms to indicate hybrid status, such as nothospecies and nothogenus.
• Binary Naming Conventions:
  • Interspecific Hybrids: Follow a binary naming system with the multiplication sign before the specific epithet, simplifying communication about hybrids.
• Variant Naming:
  • Nothosubspecies and Nothovarieties: Provide additional detail about specific variations within an interspecific hybrid, ensuring precise classification.
• Intergeneric Hybrids:
  • Condensed Formula: Combines parts of the names from the parent genera to create a hybrid name, making it easier to identify the genetic composition.
• Complex Hybrids:
  • Nothogeneric Names: Incorporate a personal name with a standardized suffix to manage the complexity of hybrids involving multiple genera.
• Grafts:
  • Plus Sign (+): Indicates physical grafting rather than genetic hybridization, clarifying the method of combination.

Rule 9 – Names of Cultivated Plants

The nomenclature of cultivated plants follows specific rules outlined in the International Code of Nomenclature for Cultivated Plants (ICNCP). This system, while largely derived from the broader International Code of Nomenclature (ICN), introduces distinct conventions tailored to the classification and naming of cultivated varieties. Below is an overview of the principles governing the names of cultivated plants:

General Principles

1. Cultivar Designation
   • Description: Cultivars, which are cultivated varieties, are designated using the abbreviation cv. or within single quotation marks (‘ ’). These names are typically common names rather than Latin terms.
   • Format: Cultivar names are written with an initial capital letter and are not italicized.
   • Examples: Rosa floribunda cv. Blessings or Rosa floribunda ‘Blessings’.
2. Nomenclatural Conventions
   • Description: The ICNCP stipulates that cultivar names must follow specific formatting rules to differentiate them from botanical names. The cultivar name is presented in plain text and capitalized, distinguishing it from Latin binomial nomenclature.
   • Details: For example, Rosa floribunda is the species name, and ‘Blessings’ represents the cultivar within that species.

Detailed Explanations

• Cultivar Abbreviation (cv.):
  • Usage: The abbreviation cv. is used to precede the cultivar name, indicating the specific cultivated variety within a species.
  • Example: Rosa floribunda cv. Blessings shows that “Blessings” is a cultivar of the Rosa floribunda species.
• Cultivar Names in Single Quotation Marks (‘ ’):
  • Usage: Alternatively, cultivar names are enclosed in single quotation marks to denote their status as cultivated varieties.
  • Example: Rosa floribunda ‘Blessings’ signifies that “Blessings” is a specific cultivar of Rosa floribunda.
• Non-Italicized and Capitalized Names:
  • Description: Unlike botanical names, cultivar names are not italicized. They are written with an initial capital letter, following standard naming conventions for cultivated plants.
  • Example: The proper format is Rosa floribunda ‘Blessings’, where “Blessings” is capitalized and not italicized.

Application and Functions

• Clarity in Cultivar Identification:
  • Description: These naming conventions ensure that cultivated varieties are easily identifiable and distinguishable from their botanical counterparts.
  • Importance: By adhering to these rules, horticulturists and botanists can effectively communicate about specific plant varieties, avoiding confusion.
• Consistency in Botanical Literature:
  • Description: The consistent application of these conventions across scientific literature and horticultural practice helps maintain standardized communication regarding cultivated plants.
  • Impact: This consistency is crucial for accurate documentation, research, and cultivation of plant varieties.

Rule 10 – Nomina Conservanda (nom.cons.)

Nomina Conservanda (Latin for “conserved names”) refers to a set of rules established within botanical nomenclature to preserve the stability and continuity of scientific names. This system addresses the complexities and potential confusion that arise from strictly applying the principle of priority, which could otherwise result in frequent and disruptive name changes. Here is a detailed examination of Nomina Conservanda:

Overview

1. Purpose of Nomina Conservanda
   • Objective: Nomina conservanda is designed to prevent the frequent alteration of well-known names of plants, especially those encompassing numerous species or significant historical usage.
   • Application: The Code includes a list of these conserved names, which are recognized as valid replacements for earlier legitimate names that are otherwise rejected.
2. Principle of Priority
   • Description: The principle of priority dictates that the earliest validly published name for a taxon should be used. However, this can lead to the replacement of well-established names with less familiar or cumbersome ones.
   • Consequence: To avoid confusion and ensure stability, the principle of priority may be overridden by nomina conservanda.

Examples of Conserved Names

1. Triticum aestivum L.
   • Description: Commonly known as wheat, Triticum aestivum is the first species conserved to maintain its widely recognized name over any earlier alternatives.
2. Lycopersicon esculentum Mill.
   • Description: This name refers to the tomato, a widely studied and economically important plant whose name is preserved to maintain consistency in scientific communication.
3. Allium ampeloprasum L.
   • Description: Known as the elephant garlic or great garlic, this species is conserved to ensure stability in its nomenclature.
4. Amaryllis belladonna L.
   • Description: Commonly called the belladonna lily, this plant’s name is conserved to preserve its historical and horticultural significance.
5. Bombax ceiba L.
   • Description: This name refers to the silk cotton tree, which is conserved to maintain consistency in its scientific classification.
6. Carex filicina Nees.
   • Description: This name pertains to a species of sedge, and its conservation ensures the continuity of its established scientific name.
7. Hedysarum cornutum L.
   • Description: Known as the horned sweet pea, the conservation of this name helps avoid confusion with other species.
8. Magnolia kobus DC.
   • Description: This name pertains to the Kobus magnolia, conserved to preserve its widely accepted scientific designation.
9. Silene gallica L.
   • Description: Commonly referred to as the French catchfly, this name is preserved to maintain clarity in botanical literature.

Detailed Explanation

• Conserved Names List
  • Description: A formal list of conserved names is maintained and published in botanical nomenclature codes. This list helps to standardize the names of various plant families and genera, ensuring that established names are retained over potentially confusing alternatives.
• Replacement of Rejected Names
  • Description: The earlier legitimate names that are replaced by conserved names are termed nomina rejicienda (rejected names). These rejected names are no longer used in formal nomenclature to avoid confusion.

Functions and Impact

• Stability in Nomenclature
  • Description: By conserving well-established names, the system reduces the frequency of name changes, thereby supporting stability and continuity in botanical research and communication.
• Consistency in Scientific Communication
  • Description: Conserved names facilitate clearer and more consistent communication among botanists, researchers, and horticulturists, preventing the misuse or confusion of plant names.

Rule 11 – Retention of Specific and Infra-specific Epithets

In botanical nomenclature, the retention of specific and infra-specific epithets plays a vital role in maintaining consistency and clarity in plant naming conventions. This process is governed by rules designed to preserve the stability of plant names even when changes occur at higher taxonomic levels, such as the genus. Here is a detailed explanation of how specific and infra-specific epithets are handled:

General Principles

1. Definition of Epithets
   • Specific Epithet: The specific epithet is the second part of a binomial name, following the genus name. It uniquely identifies a species within a genus.
   • Infra-specific Epithets: These are used in the naming of varieties, subspecies, and forms within a species.
2. Retention During Genus Transfer
   • Objective: When a species is moved to a different genus, the specific epithet must be retained to preserve the established identity of the species.
   • Procedure: The genus name is updated while keeping the original specific epithet intact, ensuring that the species name remains recognizable and consistent.

Detailed Mechanisms

1. Transfer of a Species
   • Process: If a species is reclassified into a new genus, the specific epithet is carried over to the new genus without modification. For example, if Hibiscus rosa-sinensis is transferred to a new genus Gossypibiscus, the name becomes Gossypibiscus rosa-sinensis.
   • Rationale: This practice helps avoid confusion and maintains continuity in the scientific literature and databases.
2. Changes in Genus Name
   • Illegitimate Names: If a genus name is deemed illegitimate and replaced with a new one, the specific epithets of all species within that genus are retained. This ensures that each species maintains its established identity.
   • Implementation: The new generic name is used in conjunction with the original specific epithets. For instance, if Carya ovata (formerly in Carya) is moved to a newly valid genus, it will be named accordingly while preserving ovata.

Infra-specific Epithets

1. Retention of Varieties and Subspecies
   • Description: When infra-specific taxa such as varieties or subspecies are moved to a new genus, their epithets are also retained. For example, a variety Gossypium hirsutum var. marie would retain its epithet if transferred to a different genus.
   • Significance: This practice ensures that the detailed classification within a species remains stable, even if the species’ generic classification changes.
2. Consistency in Naming
   • Function: Retaining infra-specific epithets maintains consistency in the classification of plant varieties and forms. This is crucial for researchers, horticulturists, and conservationists who rely on precise taxonomic information.

Example of Retention

• Example: If the genus Caryophyllus is replaced with Dianthus and contains the species Caryophyllus barbatus, the new name would be Dianthus barbatus, retaining the specific epithet barbatus.

Rule 12 – Splitting of a Genus

The process of splitting a genus involves dividing an existing genus into two or more distinct genera. This action necessitates adherence to specific nomenclatural rules to ensure consistency and stability in botanical classification. Here is a detailed examination of how the splitting of a genus is managed:

General Principles

1. Retaining the Original Generic Name
   • Objective: When a genus is split, the original generic name must be retained for one of the newly created genera. This genus, termed as the “retained genus,” will include the type species of the original, undivided genus.
   • Purpose: This practice preserves the stability of nomenclature and ensures that the historical and scientific context of the original genus is maintained.
2. Application to Species Division
   • Consistency: The same principle applies when species within a genus are divided into separate species. The original species name is retained for one of the new species to maintain continuity.

Detailed Mechanism

1. Retention of the Original Name
   • Process: When a genus is divided, one of the new genera retains the original name. This genus will include the type species—the species that was originally designated as the representative of the genus.
   • Example: If the genus Caryophyllus is divided into Caryophyllus and Dianthus, and Caryophyllus retains the type species of the original genus, then Caryophyllus will continue to use its original name.
2. Naming of New Genera
   • Procedure: The newly established genera, other than the retained one, will be assigned new names. These names must be validly published and should adhere to the rules of botanical nomenclature.
   • Example: Following the division, the genus Dianthus would be named according to its new designation and must be unique from Caryophyllus.
3. Impact on Taxonomy
   • Stability: By retaining the original name for one genus, taxonomic stability is achieved. This prevents confusion and preserves the continuity of scientific names across taxonomic revisions.
   • Documentation: Detailed documentation of the split, including the type species and the reasons for the split, is essential for accurate historical and scientific reference.

Examples of Division

1. Botanical Example
   • Scenario: Consider a scenario where the genus Dianthus is split into Dianthus and Petrorhagia. Dianthus retains the type species of the original genus, while Petrorhagia is given a new name.
   • Result: Dianthus will maintain its original name, while Petrorhagia will be identified as a new genus with a new name.
2. Species Division
   • Scenario: If a species such as Dianthus caryophyllus is split into multiple species, the name Dianthus caryophyllus may be retained for one of the new species, while others receive new names.
   • Result: This approach ensures that the historical and scientific context of Dianthus caryophyllus is preserved in the nomenclature.

References

1. https://northgauhaticollegeonline.co.in/attendence/classnotes/files/1716052056.pdf
2. https://egyankosh.ac.in/bitstream/123456789/57301/1/Unit-17_CRC_Formatted.pdf
3. https://bpchalihacollege.org.in/online/attendence/classnotes/files/1624862542.pdf
4. https://jagiroadcollegelive.co.in/attendence/classnotes/files/1587290512.pdf
5. https://www.hcpgcollege.edu.in/sites/default/files/3rd%20SEM%20Botanical%20Nomenclature.pdf
6. https://dducollegedu.ac.in/Datafiles/cms/ecourse%20content/Nomenclature.pdf
7. https://www.biologydiscussion.com/plant-taxonomy/nomenclature-plant-taxonomy/icbninternational-code-of-botanical-nomenclature/30308
8. https://www.biologydiscussion.com/angiosperm/taxonomy-angiosperm/international-code-of-botanical-nomenclature-icbn-taxonomy/34705
9. https://www.uou.ac.in/lecturenotes/science/MSCBOT-17/Paper%20Code-BOT503%20(Gymnosperms,%20Taxonomy%20of%20Angiosperms%20and%20Anatomy).pdf