Alpha taxonomy or classical taxonomy : It is based on external morphology characters of plants.
Beta taxonomy : Besides external morphology, it also includes internal characters like embryological,
cytological, anatomical characters etc.
Omega taxonomy : Omega taxonomy has widest scope. It is based on all the information or data available about plants.
Cytotaxonomy : The use of cytological characters of plants in classification or in solving taxonomic problems is called cytotaxonomy. Cytological characters constitute an important aid to plant taxonomy, especially in determining affinities at the generic and infrageneric levels.
Chemotaxonomy : The uses of chemical characters of plants in classification or in solving taxonomic problems is called chemotaxonomy or chemical taxonomy. It is based on the chemical constitution of plants. The fragrance and taste vary from species to species. The basic chemical compounds used in chemotaxonomy are alkaloids, carotenoids, tannins, polysaccharide, nucleic acids, fatty acids, amino acids, aromatic compounds etc.
Karyotaxonomy : Based on characters of nucleus and chromosomes. Pattern of chromosomal bands (dark bands and light bands) is most specific characters.