R.H. whittaker (1969) has proposed five kingdom system of classification of living organisms on the basis of
(i) Prokaryotic and eukaryotc nature
(ii) Unicellularity and mukiceUi/larity
(iii) Mode of nutrition and
(iv) Phylogenetic relationships.
[a] Monera: The kingdom includes all prokaryotes i.e., mycoplasma, rickettsiae, archaebacteria, eubacteria, Actinomycetes and cyanobacteria.
[b] Protista: It contains unicellular and colonial eukaryote like flagellates, diatoms, dinoflagellates, slime moulds, sarcodines ciliates and sporozoans.
[c] Fungi: This kingdom is of achlorophillous, spore producing, multiceUular or multinucleate eukaryotic organisms having absorptive type of nutrition (either saprophytic or parasitic).
[d] Plaintae: These are multicellular eukaryotic photosynthetic organisms and their close relatives e.g., green algae, brown algae, red algae, bryophvtes, pteridophytes and spermatophytes.
[e] Animalia: This kingdom contains multicellular eukaryotic organisms having ingestive type of nutrition, regular body form, internal organs, growth definite but diffused, occurrence of tissue and organ system level of organisation etc.