nodum In plant ecology, a characteristic vegetation unit. The term was first applied by M. E. D. Poore (1956) to similar sites grouped together using modified, traditional, phytosociological techniques. It was applied by J. M. Lambert and W. L. T. Williams in 1962 to vegetation units doubly defined in nodal analysis, i.e. cases in which examination of groups identified by normal and inverse classification of a data set showed complete coincidence of indicator sites and species. A sub-nodum occurs when coincidence of indicator parameters occurs in one direction only. See also INVERSE ANALYSIS.

nodum In plant ecology, a characteristic vegetation unit. The term was first applied by M. E. D. Poore (1956) to similar sites grouped together, using modified, traditional, phytosociological techniques.