PLANTWATCH AI · GLOBAL PLANT PATHOLOGY

Plant Classification and Taxonomy

Taxonomy groups organisms by shared features: Kingdom, Division (Phylum), Class, Order, Family, Genus, Species. Every plant has a two-part Latin name, e.g. Zea mays (maize).

Botany · Secondary / Diploma / Degree

Diagram of the biological classification hierarchy from domain to species
Diagram of the biological classification hierarchy from domain to species · Wikimedia Commons

Learning objectives

  • List the taxonomic ranks in order
  • Write scientific names correctly
  • Describe the four major plant groups with examples

1. Hierarchy and naming

The ranks are Kingdom → Division → Class → Order → Family → Genus → Species. Binomial nomenclature, introduced by Carl Linnaeus, gives each species a genus name (capital letter) and species epithet (lower case), both italicised or underlined when handwritten: Oryza sativa (rice), Manihot esculenta (cassava).

2. Major plant groups

Bryophytes (mosses, liverworts) lack vascular tissue and need water for fertilisation. Pteridophytes (ferns) have xylem and phloem but reproduce by spores. Gymnosperms (pines, cycads) bear naked seeds in cones. Angiosperms (flowering plants) enclose seeds in fruits and are split into monocots and dicots.

  • Non-vascular: bryophytes
  • Vascular, seedless: pteridophytes
  • Seed plants: gymnosperms and angiosperms

Key definitions

Taxonomy
The science of naming, describing and classifying organisms.
Species
A group of similar organisms that can interbreed to produce fertile offspring.
Angiosperm
A flowering plant whose seeds are enclosed within an ovary (fruit).

Exam tips

  • Use the mnemonic 'King David Came Over For Good Soup' for the ranks.
  • Underline both parts of a scientific name when handwriting — you lose marks if you don't.

Practice exam questions & model answers

Q1.Distinguish between gymnosperms and angiosperms.

Gymnosperms bear naked seeds, usually in cones, have no flowers or fruits, and mostly have needle-like leaves (e.g. pine). Angiosperms produce flowers, and their seeds are enclosed in a fruit developed from the ovary (e.g. maize, mango).

Q2.Give the scientific names of three crops and state the rules for writing them.

Zea mays (maize), Oryza sativa (rice), Manihot esculenta (cassava). The genus begins with a capital letter, the species epithet with a small letter, and the whole name is italicised in print or underlined separately when handwritten.

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