There are more than 1000 species of bryophytes in Sweden, about four times the number of breeding bird species. They all look different and they all have their own combination of characters with respect to habitat, life-history and relations to other organisms.  There are three major groups of bryophytes – mosses, liverworts and hornworts – which are fairly different.  They share the common trait of having a life cycle in which the dominant generation is haploid, with a single set of chromosomes in each cell, whereas the diploid generation, with two sets of chromosomes in each cell, is short-lived. This triggered my curiosity already when I was at undergraduate level, because almost all well-studied multicellular organisms (including humans) have a dominant diploid generation.

Throughout my scientific career I have sought answer for a few fundamental questions:

• How is genetic variability maintained despite a dominant haploid life cycle?

• How can bryophytes overcome the inconvenience of having antherozoids that need a water layer to reach the females?

• Is hybridization between species important for evolutionary processes in bryophytes?

• How does a limited structural complexity of bryophytes compare with chemical and genomic complexity?

These questions may seem specific to bryophytes, but in the real life they have bearings of our understanding of the evolution of all organisms. If we only collect information from diploid plants and animals, we get a false and one-eyed impression of nature. Bryophytes have been understudied from genetic point of view for a long time, just like several other groups of organisms that are collectively known as “Cryptogams”, a term coined by Linneaus for organisms that he did not understand how they reproduced!