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🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Rules Of Nomenclature
Why We Need Rules for Naming
Imagine you walk into a library where every book has a different title written in a different language, some books have no title at all, and others share the same title. That chaos is exactly what biology faced before standardised naming. A "robin" in England is a different bird from a "robin" in America. A "banyan tree" in one village might mean a completely different species in another. Without rules, scientists cannot know if they are talking about the same organism.
The solution is a universal system that gives every living thing one unique, internationally accepted name. This system is governed by two sets of rules: the International Code of Botanical Nomenclature (ICBN) for plants, fungi, and algae, and the International Code of Zoological Nomenclature (ICZN) for animals. The principles are nearly identical, so we can learn them together.
The Core Idea: Binomial Nomenclature
Every recognised species gets a two-word Latin name. The first word is the genus (a group of closely related species), and the second word is the specific epithet (which identifies the exact species within that genus). Together, they form the scientific name.
Scientific Name=Genus (capitalised)+species (lowercase)
For example, the modern human is Homo sapiens. Homo is the genus (which includes extinct relatives like Homo erectus), and sapiens means "wise" — it distinguishes us from other Homo species.
The Five Hard Rules
These are not suggestions. They are mandatory for a name to be valid.
1. The name must be Latinised. Even if the root word comes from Greek, a person's name, or a place, it must be given a Latin ending. For instance, mango becomes Mangifera indica (where indica means "from India").
2. The name must be italicised (or underlined if handwritten). This visually separates the scientific name from the surrounding text. In print, you write Mangifera indica; by hand, you underline it.
3. The genus name starts with a capital letter; the species epithet starts with a small letter. Always. Even if the species is named after a person (like Rosa banksiae — named after Lady Banks), the species part stays lowercase.
4. The author's name (or abbreviation) is written at the end. This credits the scientist who first described and named the species. For example, Mangifera indica L. — the "L." stands for Linnaeus. This helps trace the original description if there is ever a dispute.
5. No two species can share the same name. This is the entire point. Once a name is validly published, it is the only accepted name for that organism. If two scientists accidentally name the same species differently, the older published name takes priority.
A common mistake is writing the species epithet with a capital letter (e.g., Homo Sapiens). This is incorrect. The species part is always lowercase, even if it is derived from a proper noun.
Why Latin? Why Not English? …
These are the two internationally agreed rule-books that govern the scientific naming of plants and of animals respectively. …
ICBN is the International Code of Botanical Nomenclature and ICZN is the International Code of Zoological Nomenclature.
Biologists follow agreed international codes so that every organism has one correct, universally accepted scientific name.
- (a) ICBN - International Code of Botanical Nomenclature, which lays down the rules for naming plants. …
- CBSE 2025Set ANNUAL1 markQ.Choose True or False: The first word in 'Mangifera indica' indicates the species name.
›Reveal solutionSolution
The statement is False — in binomial nomenclature, the first word is the genus, not the species.
Under the binomial nomenclature system (given by Carolus Linnaeus and followed universally), every scientific name has two parts: the first word denotes the genus and starts with a capital letter, and the second word denotes the specific epithet (species) and is written in lower case. In 'Mangifera indica' (mango), 'Mangifera' is the genus and 'indica' is the s …
- CBSE 2025Set ANN1 markQ.Expand(a) ICBN(b) ICZN
›Reveal solutionSolution
ICBN is the International Code of Botanical Nomenclature and ICZN is the International Code of Zoological Nomenclature.
Biologists follow agreed international codes so that every organism has one correct, universally accepted scientific name.
- (a) ICBN - International Code of Botanical Nomenclature, which lays down the rules for naming plants. …
- CBSE 2023Set ANN1 markQ.Scientific name of lion is given below. Which one is correctly written ?
›Reveal solutionSolution
Correct binomial nomenclature requires the genus name to start with a capital letter, the species name to be in lower case, and both to be printed in italics — so "Panthera leo" is correct.
Rules of binomial nomenclature (as per ICZN/ICBN conventions):
- The generic name begins with a capital letter.
- The specific epithet (species name) begins with a lower-case letter.
- Both names are written in italics (or individually underlined when handwritten). …
- CBSE 2023Set botany1 markQ.What does ICBN stand for?
›Reveal solutionSolution
ICBN = International Code of Botanical Nomenclature, the internationally agreed rulebook for naming plants scientifically.
Just as animals are named according to the International Code of Zoological Nomenclature (ICZN), plants are named following a separate, internationally agreed set of rules called the International Code of Botanical Nomenclature (ICBN). This code lays down the principles and rules for the formation and use of scientific (Latinised, binomial) names for plants, ensuring that:
- Every plant species is given exactly one correct, universally accepted scientific name.
- The same name is not used for two different plants, and the same plant is not given two different valid names, avoiding confusion across countries and languages.
- Names follow the binomial system introduced by Linnaeus (genus + specific epithet), are always Latinised, and the genus name is capitalised while the species name is not, both written in italics (or underlined when handwritten). …
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