Classification a


Humans classify almost everything, including each other. This habit can be quite useful. For example, when talking about a car someone might describe it as a 4-door sedan with a fuel injected V-8 engine. A knowledgeable listener who has not seen the car will still have a good idea of what it is like because of certain characteristics it shares with other familiar cars. Humans have been classifying plants and animals for a lot longer than they have been classifying cars, but the principle is much the same. In fact, one of the central problems in biology is the classification of organisms on the basis of shared characteristics. As an example, biologists classify all organisms with a backbone as “vertebrates.” In this case the backbone is a characteristic that defines the group. If, in addition to a backbone, an organism has gills and fins it is a fish, a subcategory of the vertebrates. This fish can be further assigned to smaller and smaller categories down to the level of the species. The classification of organisms in this way aids the biologist by bringing order to what would otherwise be a bewildering diversity of species. (There are probably several million species ‑ of which about one million have been named and classified.) The field devoted to the classification of organisms is called taxonomy [Gk. taxis, arrange, put in order + nomos, law].

(Father of taxonomy)

Carolus Linnaeus

He is known as the “father of modern taxonomy”. Many of his writings were in Latin, and his name is rendered in Latin as Carolus Linnæus (after 1761 Carolus a Linné). Linnaeus was born in the countryside of Småland in southern Sweden.


Taxonomy (from ancient word (taxis), meaning ‘arrangement’, and -νομία (-nomia), meaning ‘method‘) is the science of defining and naming groups of biological organisms on the basis of shared characteristics. Organisms are grouped together into taxa (singular: taxon) and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a super-group of higher rank, thus creating a taxonomic hierarchy. The principal ranks in modern use are domain, kingdom, phylum (division is sometimes used in botany in place of phylum), class, order, family, genus and species. The Swedish botanist Carl Linnaeus is regarded as the father of taxonomy, as he developed a system known as Linnaean taxonomy for categorization of organisms and binomial nomenclature for naming organisms.

With the advent of such fields of study as phylogenetics, cladistics, and systematics, the Linnaean system has progressed to a system of modern biological classification based on the evolutionary relationships between organisms, both living and extinct.

Hierarch classification

Hierarchical Classification is a system of grouping things according to a hierarchy, or levels and orders. … The categorization of species is another example of hierarchical classification. At the very top is the kingdom which is the broadest category, followed by phylum, class, order, family, genus, and species.

Ernst Haeckel

THALLOPHYTA ( gk. Thallos–undiffierentiate. -plant)

It is division of plantae in which the plants do not have a well differentiates body design.


  1. Simple body .The body design is simple and is often called thallus.
  2. Reproduction organs .they are unicellular and non jacketed.
  3. Embryo stage.Absent.

4.Vascular tissue: absent


They are THALLOPHYTA which are capable of manufacturing their own food through photosynthesis.

Algae are most aquatic .only a few of them occur in moist terrestrial habitat.


  1. The common forms of algae are thread – like ( branched or unbranched) filament and parenchymatous thallus.
  2. Algae are of three main group — green ,red and brown .Red and brown colour are due to presence of large amount of accessory photosynthetic pigment in addition to chlorophyll.
  3. Mucilage . The plant body is covered over by mucilage
  4. Nutrition. Photosynthetic
  5. Cell wall. It contain cellulose.
  6. Reserve food. It is generally starch or some related chemical.

Example . Ulothrix, spirogyra, ( both unbranched filaments) ; Cladophora, chara, ( branched filament) ,ulva( flat,parenchymatons thallus).


Both the spores and the resultinggametophyte are haploid, meaning they only have one set of chromosomes. The maturegametophyte produces male or female gametes (or both) by mitosis. The fusion of male and female gametes produces a diploid zygote which develops into a new sporophyte.





Dicot and Monocot


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