Abstract
The antigenic properties of some putative hybrid individuals from a hybrid swarm population were studied. All the plants were to a major or lesser degree intermediate between three pure taxa, i.e. P. sylvestris, P. mugo and P. uliginosa. The plants are, however, not intermediate in general, but are sin-Mar to one species in part of their antigenic properties (enzymatic systems) and to the other one in the rest. It means that there is no common trend in the variation of the antigenic characters (proteins) and they behave independently.