Herbarium Labels, Synonyms and the Rules of Nomenclature
A team of four Class XI students prepares a herbarium for the district science exhibition. Their labels read: (i) 'Tulsi - Ocimum sanctum Linn.'; (ii) 'Neem - Azadirachta indica A.Juss.'; (iii) 'Vallarai - Centella asiatica (L.) Urban'; (iv) 'a grass collected near the canal, name not known'. A teacher points out that the tulsi specimen is now placed under the accepted name Ocimum tenuiflorum L., because the two names refer to the same species and only the accepted name may be used on a scientific label. The students also write 'Mango, Musa, Rose, Homo' in a single column headed 'species'. The zoology student adds a butterfly labelled only 'Blue butterfly'. The judge asks the team to make the herbarium acceptable under the International Code of Nomenclature and to explain how they would decide between two competing names for one plant. They have one day before judging.
1. Which name should finally appear on the tulsi label, and what must the team check before choosing between two competing names for the same plant?
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The label must carry one accepted binomial, not two. Before choosing, the team must check three things in order. First, valid publication - was the name effectively published with a description or diagnosis and a type specimen? A name used only in a school project or a nursery catalogue has no standing. Second, priority - among validly published legitimate names for the same taxon, the earliest one is correct, unless it has been officially conserved or rejected. Third, synonymy - if the two names are based on the same type specimen they are homotypic synonyms; if on different types, heterotypic synonyms, and the older legitimate name wins.
Applying this, the team should use Ocimum tenuiflorum L. and record O. sanctum L. as a synonym in the notes rather than on the label. The author citation matters too: 'L.' means Linnaeus described it, and in Centella asiatica (L.) Urban the brackets show Linnaeus published the basionym while Urban later transferred it to another genus. A label that mixes common names, synonyms and incomplete author citations is rejected not because the plant is wrong but because the naming is ambiguous.
2. The column 'Mango, Musa, Rose, Homo' is headed 'species'. Identify the error in each entry and rewrite the list correctly.
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Every entry breaks the binomial rule differently, so each needs a different correction.
- Mango is a common name, not a scientific name. Common names are regional and unstable - the same fruit has different names in Tamil, Hindi and English - so the Code does not recognise them. Correct form: Mangifera indica L.
- Musa is only the genus; a binomial needs the specific epithet. Correct form: Musa paradisiaca L. (or Musa balbisiana for the other parent of the cultivated banana).
- Rose is again a common name, and it is also the English for the genus Rosa; the species must be named, for example Rosa chinensis Jacq.
- Homo is a genus, and man is Homo sapiens L.
The rewritten column should contain four two-word italicised names, with the genus capitalised and the specific epithet in lower case, followed by the author abbreviation. If the students want to show a genus with an unidentified species they may write Rosa sp., but 'Rose' alone is not an acceptable species name in any column of a scientific herbarium.
3. How should the unnamed grass and the 'Blue butterfly' be handled so that the exhibit is scientifically defensible?
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An unnamed specimen is not a failure; an unlabelled or wrongly labelled one is. For the grass, the students cannot invent a binomial. They should run it through a flora key, compare spikelet and ligule features, and label it Poaceae sp. (unidentified), with the collector's name, locality, date and habitat. A genus name plus 'sp.' honestly signals identification to family or genus level. Inventing a name like 'Grassus canalensis' would be a nomenclatural offence, and a genuinely new species would require a Latin diagnosis, a designated type specimen deposited in a recognised herbarium and effective publication - impossible in one day.
The butterfly is worse, because 'Blue butterfly' is a common name shared by many lycaenids. The student must key it out to genus and species, confirm with a standard field guide or an expert, and record host plant, wing span and collection locality. A voucher photograph with date and place is acceptable supporting evidence for the exhibit.
The judgement the judge is testing: taxonomy demands verifiable identity plus a traceable record, not confident-looking labels.