The epiphytic microfloral population on damaged and non-damaged leaf surfaces of Polymnia sonchifolia (Compositae) was examined, and metabolic properties of microbes predominant on the damaged leaves were studied. On the damaged leaf surface, some epiphytic Gram-negative bacteria able to metabolize phenolic compounds of plant origin were highly ascendant. The most dominant bacterium, Pseudomonas viridiflava had a high activity of peroxidase on pyrocatechol, while the second major bacterium Phyllobacterium myrsinacearum, produced 4-hydroxycinnamate decarboxylase. Thus, it was likely that epiphytic bacteria predominant on damaged leaves can metabolize plant phenolics. These epiphytic bacteria frequently formed mixed colonies during their isolation, and the mixed colonies were retarded in their growing rate compared with single colonies of each.