Plants are one of the five main groups of living things. These groups are called kingdoms. The plant kingdom includes such living things as grasses, trees, ferns, bushes, and flowers. Botanists, the scientists who study plants, have counted more than 300,000 species (kinds) of plants.

Plant Classification:

  • In order to study the billions of different organisms living on Earth, scientists have sorted and classified them based on their similarities and differences.
  • This system of classification is also called taxonomy and usually features both English and Latin names for different divisions

Theophrastus 370-285 B.C. : He was a Greek philosopher and naturalist and is often called the “Father of Botany.”

Carolus Linnaeus 1707-1778 : Linnaeus was the first person to propose an orderly system for classifying organisms. He developed the Binomial System of Naming Plants in 1753. He is called Father of Taxonomy.

  • Bi= 2
  • Nomial = name
  • All plants have a scientific name composed of two Latin names known as a genus and specie

A tribe is a taxonomic rank above genus, but below family and subfamily. It is sometimes subdivided into subtribes. By convention, all taxonomic ranks above genus are capitalized, including both tribe and subtribe.

Example of Classification: Common Name: Corn Plant

CategoryScientific Name
KingdomPlantae
PhylumSpermatophyta
ClassAngiospermae
Sub-classMonocotyledonae
FamilyGramine
GenusZea
SpeciesMays

Levels of Classification of Plants:

There are three levels of classification among plants.

  • The first level of classification among plants depends on whether the plant body has well- differentiated, distinct components. Depending upon this criteria plants are classified as Thallophyta, Bryophyta, and Pteridophyta. The thallophytes, the bryophytes, and the pteridophytes have inconspicuous reproductive organs hence they are therefore called ‘cryptogamae’, or ‘those with hidden reproductive organs’.
  • The second level of classification is based on whether the differentiated plant body has special tissues for the transport of water (xylem) and other substances (phloem)within it. Depending upon this criteria plants are classified as vascular (having xylem and phloem)   and non-vascular (not having xylem and phloem)
  • The next level of classification is based on seed producing and non-seed producing. If seed producing then on the basis whether the seed is enclosed or not.
  • In 1883, Eichler divided the kingdom Plantae into two sub-kingdoms, Cryptogamae and Phanerogamae.

I. Cryptogams:

Cryptogams never bear flowers and reproduce by some minute bodies called spores, or by simple fission. They are again divided into three groups:

  1. Thallophyta: A thallophyte is that plant where the plant body is an undifferentiated mass of cells (thallus), having nothing like stems, roots and leaves. The green thallophytes which usually grow in water are called algae, e.g. pond-scum; and non-green thallophytes are the fungi. The common moulds growing on rotten organic substances and mushrooms, belong to this group.
  2. Bryophyta: This group includes plants like mosses with small stems and simple leaves but no roots. They grow in moist places often forming something like green velvety carpet. Some bryophytes have thalloid bodies
  3. Pteridophyta: Here the plant body is well differentiated into roots, stems and leaves, and the organs have well-developed conducting strands. These are the highest cryptogams also known as vascular cryptogams. Ferns are the familiar examples.

II. Spermatophytes or Phanerogams

These are the higher plants. They bear flowers and reproduce by means of seeds. They are of two types:

  • Gymnosperms (gymnos = naked; sperma = seed): Gymnosperms are the naked-seeded plants where the seeds remain exposed;
  • Angiosperms (angeion—a case): angiosperms are closed-seeded ones where seeds are covered, that is, remain inside the fruits.

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