Every individual interacts in a variety of ways with a number of other individuals. Individuals of the same species, if situated spatially and temporally near enough to each other, compete, though ramets may compete or act as reservoirs of supply for each other according to circumstance. This is a simplified view of intraspecific relationships.

Species associations are interspecific relationships, and the following account must needs take the form of a rather broad review, since information derived directly from observation in West Africa is quite limited.

Interspecific organismal associations were termed symbioses by De Bary (1879), and a number of kinds of such relationship is now recognised. The named kinds are obviously different from each other, but there may well exist more such relationships, differing from each other in subtle and, as yet, undiscovered ways.

It is proposed to define symbiosis as provision by permanent or transient physical contact of one species for another. At least one nutrient or service of significance for the survival of at least one of the participants is involved and some degree of obligacy is present in the relationship.

This definition is wider than that of Boucher, James & Keeler (1982), but narrower than that of Starr (1975). It includes mutualism, in which the associate species confer benefit (exchange nutrients/services) on each other.