For some 50 years, Professor Asakawa and his group have focused their
research on the chemical constituents of bryophytes and have found that
these plants contain large numbers of secondary metabolites, such as
terpenoids, acetogenins, and aromatic compounds representative of many
new skeletons, which exhibit interesting biological activities.
Individual terpenoids, when found as constituents of both a bryophyte
and a higher plant, tend to occur in different enantiomeric forms.
Professor Asakawa has covered the literature on bryophytes in two
earlier volumes of Progress in the Chemistry of Organic Natural
Products, namely, Volumes 42 (1982) and 65 (1995). Since the
publication of the latter volume, a great deal of new information has
appeared on bryophytes. One example is that known sex pheromones of
algae have been discovered in two liverworts, indicating that some
members of the latter taxonomic group might originate from brown algae.
From information provided in this volume, it is suggested that two
orders of the Marchantiophyta should be combined.