Histochemical Tests for Polyphenols in Plant Tissues

A satisfactory histochemical test for polyphenols in fresh plant tissues is described. The test is based upon a colorimetric method for phenolics using a nitrous acid reaction. Certain catechol derivatives are characterized by the formation of an intense cherry-red in fresh sections of plant tissues with the reagents used. The red color is sufficiently intense to be readily observed microscopically at 100X. Results obtained with other tests also are described.