Ferns and their spore-producing allies the lycopods and horsetails are unique among land plants in having two free-living generations, both usually photosynthetic, one with half and one with a full complement of chromosomes. The complete life cycle of a fern requires an alternation between the small haploid stage, at which sexual reproduction is effected, and the larger sporophyte or "frond" stage at which spores are produced, for dispersal by wind. Recent technical advances in the laboratory culturing of the small haploid generation, the gametophyte stage, have opened the way to molecular studies of fern growth and development and made possible the manipulation of environmental cues affecting the timing of egg and sperm maturation, fertilization, and crossing within and among populations of fern gametophytes. Molecular analyses of enzymatic proteins and of nuclear and chloroplast DNA have also opened the way to direct measurement of gene differences within and among fern species. A new set of technical tools is now available for the estimation of phylogenetic or genealogical relationships among ferns, for the tracking of geographical migrations, and for measuring genetic impoverishment in declining populations of endangered fern species. Drs. Florence Wagner and Chris Haufler have organized an international conference to focus on these new technical advances in fern biology, to be hosted by the University of Michigan and involving scientists from 20 countries. This will be the second such international gathering, since the first in 1983 in Edinburgh. NSF support will help bring collaborators from Europe, Australia, and Japan to attend the five days of meetings. Direct discussions among researchers working in otherwise separate laboratories around the world will be an additional benefit of the conference, and will facilitate a clearer focus on major problems in fern biology now amenable to solution.
