GREEN ALGAL PHYLOGENY

Studies on the fine structure of green algal cells in the 1970s fundam entally revised theories on the evolution of green algae (Division Chl orophyta) and their relation to higher and drier green plants (i.e. em bryophytes or land plants). Recent molecular phylogenetic work has lar gely confirmed some rather unorthodox proposals about which of the gre en algae represent the closest living relatives of higher plants. Reso lution of the most ancient divergences on the green algal-land plant l ineage remains elusive because of the rapidity of these evolutionary r adiations and because branch topology varies with the taxa and molecul ar sequences sampled (as well as method of analysis). Molecular analys es within green algal groups have reinforced the value of ultrastructu ral characters and challenged the use of vegetative form as an overrid ing feature in classification.