• cycle;
  • DNA C;
  • flow cytometry;
  • holoploid genome size;
  • individual growth rate;
  • life;
  • monoploid genome size;
  • nuclear DNA;
  • seed mass;
  • value

In spite of the large number of studies on genome size, studies comparing genome size and growth-related traits across a wider range of species from the same habitat, taking into account species phylogeny, are largely missing. I estimated the relationship between genome size and different seed and seedling traits in perennial herbs occurring in dry calcareous grasslands in northern Bohemia, Czech Republic. There was no relationship between genome size and plant traits in simple regression analyses, but several strong relationships emerged in analyses based on pairwise phylogenetically independent contrasts. There was a significant relationship between monoploid genome size and production of above-ground biomass, seedling establishment success and seed weight and between holoploid genome size and seed dormancy. Because the results are based on phylogenetically independent contrasts over a range of species from the same type of habitat, they allow me to conclude that these patterns were not because of species group or habitat type, but really show a correlation with genome size. In contrast to previous studies, I found a higher number of relationships with monoploid than with holoploid genome size. This may be because the traits observed in this study are directly related to plant growth and thus to life-cycle time, which is determined by monoploid genome size. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160, 290–298.