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In Białowieża Primeval Forest, in 1823 Stanisław Górski discovered on the Cisovka Hag, a relic population of European silver-fir (Abies alba Mill.). This population is isolated and most away, 120 km to the North-East, from the border of European-silver-fir distribution. Besides the natural population Cisovka, there are also man-made silver fir stands and clumps in the Polish and Belorussian part of Białowieża Primeval Forest. In the Polish part there are four such artificial stands. If the seed-producing silver-fir stands really originated from the Cisovka population, then they are a very valuable part of the declining population and an easy accessible seed source. However, if these populations were introduced to the Białowieża Primeval Forest, then they are a potential source of dangerous genetic pollution of the Cisovka population. The relationship of the genetic structure of the Cisovka population to man-made silver-fir-stands in Białowieża Forest was investigated with the help of 17 loci of 1 1 enzyme systems. Genetic diversity of Cisovka population is characterized by the smallest mean number of alleles per locus (Mal= 1.353, includes all loci studied and per polimorphic locus Malp = 2.00). In Cisovka population there is very low-grade of polimorphic loci (Pp = 11.765 with the mean 37.255 for all studied populations). Expected heterozygosity, He = 0.079 revealed very low-grade of genetic diversity in the population. The observed heterozygosity (Ho = 0.123) was similar to this characterictic in other populations. A dendrogram based on Neis genetic distance coefficient (D) among 9 silver-fir populations was constructed. Cisovka in the UPGMA dendrogram is a distinct population separated from other ones by a very great genetic distance (D = 0.06). Also two man-made silver-fir (B I and 132) stands are separated from others. Only populations B3 and B4 are combined into one subgroup linked to the population Tomaszów Lubelski. Basing on the received results one should decide that all the four studied artificial stands were introduced to Białowieża Primeval Forest from beyond of this geographical regions. There is some reason to assume (on the GDH2 allele frequency) that man-made silver-stands in compartments 453Aa and 498Cg are of eastern provenance. It is rather certain that these stands are not of offspring of Cisovka populations.

With the help of 21 putative isoenzyme loci, the genetic diversity and variations of Viscum album ssp. album L. from 42 species, subspecies, varieties and hybrids of broadleaf trees, Viscum album ssp. austriacum (Wiesb.) Vollmann, from 4 populations of Scots pine (Pinus sylvestris L.) and Viscum album ssp. abietis (Wiesb.) Abromeit, from 8 populations of European silver fir (Abies alba Mill.) were analyzed. On the dendrogram, the three investigated subspecies form three clusters, each clearly separated from the other, so we suggest a revision of the systematic nomenclature proposed to take into consideration a return to an earlier system of dividing the European mistletoe into three species: Viscum album L., Viscum abietis Beck, and Viscum laxum Boiss. et Reut. From among the 21 tested loci only one locus, SOD-A, was monomorphic. The average number of actual alleles (Na) and effective alleles (Ne) was 2.23 and 1.61 respectively. The observed heterozygosity (Ho) varied from 0.199 in V. album ssp. abietis to 0.345 in the V.a. ssp. album populations. Average FST = 0.277 indicates that about 28% of genetic differentiation is due to an interpopulation diversity of Viscum album populations. There is a small gene flux between Viscum album populations with only one immigrant successfully entering a population per two generations (Nm = 0,653).

Twenty-eight isozymic loci were studied in the Beskid Mts., in four populations of common silver-fir (Abies alba): one in Beskid Makowski (BM) and three populations in Beskid Sądecki (BS). Their genetic variation and diversity were analyzed, and Nei's genetic distances between the populations were calculated. The results show that the geographical distance between the BM population and the three BS populations is reflected in genetic distances. The BM population is clearly distinct from the others. It has the lowest genetic diversity (I = 0.42), percentage of polymorphic loci (%PoL = 64.29) and number of rare alleles (NoRa = 5). Besides, the BM population has the highest observed heterozygosity (Ho = 0.291), which exceeds the expected heterozygosity (He = 0.254), estimated on the basis of the Hardy-Weinberg Principle. On the contrary, BS populations are in the state of equilibrium, which is manifested, in similar values of He = 0.262 and Ho = 0.264.

To assess the inter- and intrapopulation genetic variation in the filial generation (F1) of alder (Alnus glutinosa (L.) Gaertn.), 11 naturally regenerated populations were analysed. Their parental populations (P), represent the whole Polish territory and belong to three phytosociological associations with alder: typical alder swamp forest Carici elongatae-Alnetum (Ce-A); alder riparian forest Circaeo-Alnetum (C-A); and ash-elm riparian forest Fraxino-Ulmetum (F-U). F1 populations are grown in a common-garden experiment (provenance trial). Genotyping of individual trees has been carried out by analysis in a bud tissue allele frequency in the 21 isozyme putative loci of 10 enzymes. Differences between populations in respect to the level of genetic diversity were not high. Genetic diversity measured as the number of effective alleles per locus was the highest (Ne = 1.65) in population Wińsko originating from F-U (where also the inbreeding coefficient was the highest, F = 0.429), and the lowest (Ne = 1.48) in population Sławki from Ce-A. In all investigated populations, observed heterozygosity (Ho = 20%) was lower than expected from H-W equilibrium (He = 29%). The highest genetic variation expressed as percentage of polymorphic loci (77.3%) was observed in the offspring populations from Ce-A, and the smallest (69.9%) in the populations originating from F-U. It seems that the low genetic differentiation between populations is probably connected with long-distance seed dispersal via river systems. Alder seed can be transported over long distances thanks to periodical flooding. There is some gene flow between alder populations, with about 2.5 immigrants successfully entering a population per generation (Nm = 2.55). The level of population subdivision within A. glutinosa was low (Fst = 0.089). There was no significant genetic differentiation between populations from different phytosociological associations. Mantel test exhibited no significant correlation (r = 0.077) between genetic and geographic distance. In the dendrogram constructed according to Nei (1972) on the basis of interpopulation genetic distances, many small groups can be observed.

Annual plant species were found to have several distinct classes of hexokinases which are specific for different hexoses, such as glucose, fructose and mannose. In conifers one isozyme of hexokinase could be found in genetic studies if only glucose was employed as substrate. If fructose was substituted for glucose, another isozyme zone different from the common hexokinase could be observed in zymograms of extracts from seed tissues of Norway spruce, Scots pine and silver fir. Hence these three conifer species possess at least two different hexokinases, glucokinase and fructokinase.