A taxonomic study of the Vaccinium sect. Oxycoccus (Hill) W.D.J. Koch (Ericaceae) in the Czech Republic and adjacent territories

The ploidy level of plants of the Vaccinium sect. Oxycocccus (HILL) W.D.J. Koch sampled in the Czech Republic, Germany, Austria and Poland was determi ned by chromosome counting and/or by flow cytometry. Forty-five characters were measured and scored in the morphometric analysis. Principal component analysis, cluster analysis, canonical discriminant analysis and classificat ory discriminant analysis were used in the statistical analyses. Diploid (2n=24), tetraploid (2n=48) and hexaploid (2n=72) populations were confirmed and a new ploidy level - pentaploid hybrid plants (2n=60) - was r evealed. Results of the multivariate morphometric analysis support the sepa ration of the two native species. Diploid V. microcarpum (TURCZ. ex RUPR.) SCHMALH. differs from the polyploids by smaller size of petals, shorter sty le and stamens (stamens have long filaments and short anthers), glabrous pe dicels, mostly solitary flowers, earlier flowering and by occurrence predom inantly in Polytichum strictum tufts. The low taxonomic significance of som e features often used in keys for their separation (shape of fruits, insert ion of prophylla, pubescence of filaments) was confirmed. V. oxycoccos L. i ncludes three ploidy levels. The hexaploids represent the most abundant plo idy level in the area studied. They show a slightly bigger size of petals, longer bracts, prophylla, style, sepal tips and wider seeds in comparison w ith the tetraploids. Pentaploid cranberries are hitherto known only from th e Czech Republic. They differ particularly in the low proportion of fully-d eveloped tetrads.