Plant Kingdom Classification and Botanical Nomenclature
This domain tests rank order, author citation and the criterion behind each classification system. One-mark questions on rank suffixes and on the type method are common, so precision of terminology matters more than breadth.
Core rules
- Hierarchy: Kingdom → Division → Class → Order → Family → Genus → Species. Botany uses Division, never phylum.
- Standard suffixes: family −aceae (Poaceae, Solanaceae), order −ales (Poales, Solanales), algal classes −phyceae, higher-plant classes −opsida.
- Binomial nomenclature: genus capitalised, specific epithet lower case, both italicised or underlined separately; author citation in roman, abbreviated - Mangifera indica L.
- Type method: every name is tied to a nomenclatural type, normally a holotype herbarium sheet. Naming is governed by the ICN (formerly ICBN); priority dates from Linnaeus, Species Plantarum, 1753.
- Systems of classification: artificial (Linnaeus's sexual system), natural (Bentham and Hooker, Genera Plantarum, 97 orders and 202 tribes), phylogenetic (Engler and Prantl, who placed monocots before dicots as "primitive"), and the molecular APG system, which groups by clades and does not rank monocots as primitive.
Worked example
Place Solanum tuberosum L. in the hierarchy. Genus Solanum; family Solanaceae, confirmed by the −aceae suffix; order Solanales; class Dicotyledonae; division Angiospermae. The "L." is the author citation for Linnaeus and must be written in roman, not italics.
Traps that cost marks
Writing "Phylum Angiospermae"; italicising the author name; describing Bentham and Hooker's system as phylogenetic (it is natural, not evolutionary); confusing the ICN with a conservation body such as IUCN.