This paper first discusses particular characteristic of the measuring and reference electrodes employed in the PHYTOGRAM technique. The technique is then summarized in terms of a normal potential range (400 to 700 mV), a hypo-potential range (50 to 400 mV) and a hyperpotential range (700 to 1400 mV). The major characteristics of each range are described in terms of hypothetical causative reactants and mechanisms: oxygen in the normal range, ethanol/acetaldehyde in the hypopotential range and hydrogen peroxide in the hyperpotential range.