As in bacterial and animal systems, the purine and pyrimidine nucleotides in plants as well as their derivatives are operative as constituents of nucleic acids and coenzymes as well as in regulatory acting Compounds. They are involved in the synthesis of thiamine, riboflavine, folic acid pteridines, histidine, or are constituents of cytokinins, purine alkaloids, and further unusual N-compounds representing one way of N-accumulation or N-excretion.