Biosystematic studies of Sorbus meinichii (Rosaceae) at Moster, S. Norway

Morphometric and cytological data were used to test the variation within the apomictic hybrid Sorbus meinichii from its type locality, in the Moster area, Bomlo in Sunnhordland, Norway. A lectotype is selected for the name. A total of 36 morphological characters were measured on leaves, stomata, flowers, pollen, fruits and seeds, from randomly selected S. meinichii individuals. In the field the material was classified into two groups, one including individuals of generally larger dimensions of leaves and fruits than the other. The preliminary classification was subsequently tested by a multivariate analysis of several characters, substantiating the existence of two morphs in the population at the type locality of S. meinichii, one corresponding to the selected lectotype. Assessment of the nature and taxonomic rank of these two morphs must await further studies. Cytological studies showed both forms of S. meinichii to be triploid, with 2n=51 chromosomes. The taxonomic separation of S. teodorii from S. nreinichii on the basis of ploidy level is therefore not corroborated. Sorbus meinichii s. lat. was shown to be intermediate between its supposed parents, S. aucuparia and S. hybrida, in several leaf characters. All of the variation within the S. aucuparia x S. hybrida-complex in Fennoscandia is better included in one aggregate species Sorbus meinichii according to the present state of knowledge.