Role of Phytochemicals and Nucleic Acids in Solving Taxonomic Problems

Phytochemicals and nucleic acids provide valuable tools for delimitation of various taxa and their placement in natural system of classification. Chemical characters are broadly categorized as visible traits, micro- and macromolecules. Compared to visible characters that are few and have limited usage in taxonomy, micro- and macromolecules provide important taxonomic tools. Micromolecular characters are small sized and include phenolic constituents, alkaloids, terpenoids, free amino acids, fats and oils and cyanogenic compounds. Macromolecules, the information containing molecules are large sized and comprise of proteins, DNA and RNA. Though chemical characters provide important taxonomic tools, some of these such as alkaloids and proteins are susceptible to change with regard to changing environmental conditions or ontogeny. Plant parts of same physiological age should, therefore be used for comparative analysis.