with the exception of Mesostigma , which, as mentioned, was positioned sister to both chlorophyte and charophyte clades. However, the analysis could not resolve with confidence the sister taxon of land plants. Karol et al. (2001) ? sampled one mitochondrial ( nad5 ), one nuclear (18S rDNA), and two plastid ( rbcL , atpB ) genes (total of 5147 nucleotides) across the major charophyte groups (26 species), plus eight land plants and six chlorophyte outgroups. Bayesian, maximum parsimony, and maximum likelihood analysis all supported monophyly of Charales and land plants. Turmel et al. (2003) ? sequenced the entire mitochondrial genome of Chara vulgaris L., and their analyses were congruent with the conclusions of Karol et al. (2001) ? . Gene loss from the mitochondrion, and group I and II intron distributions in the Chara mtDNA clearly allied this alga with that of land plant mtDNA. Maximum likelihood analysis of 23 protein sequences also strongly supported monophyly of Chara with land plants, although the number of taxa in the analysis (six) adds a note of caution to the result. Clearly, more genes and more taxa are needed to evaluate this result (Rokas et al., 2003 ? ). Extreme greens and the multiple origins of terrestrial green plants One of the exciting insights of the last few years has been the discovery of diverse green algae that can inhabit "extreme" habitats. More intensive sampling, coupled with culture-based methods and "environmental sampling," have expanded our understanding of green algal diversity and of the