Green algae are the third largest group of plants. They are especially important in freshwater ecosystems, where certain species (e.g. Cladophora) may cause nuisance growths in rivers and lakes. Others are known to produce bloom-like phenomena ('green tides') in marine coastal estuaries and lagoons (e.g. Enteromorpha).
The phylogeny of green algae
Recent phylogenetic analyses suggest that the green algae do not represent a single evolutionary lineage. Instead, the green algal tree has four distinct major branches (known as Chlorophyceae, Trebouxiophyceae, Ulvophyceae, Charophyceae) originating from a basal bunch of "primitive" flagellates often referred to as Prasinophytes.
In an evolutionary sense, the Charophyceae is of particular significance because it is regarded as the group from which all higher plants (= embryophytes, including liverworts, mosses and vascular plants) have originated. The main features of the green algal tree are now fairly well-established, following extensive work on the microscopic structure of flagella, cell division mechanisms and on recent advances in the field of molecular phylogenetics. However, for many taxa their proper place in the "tree of green plant life" remains to be determined.
Green algae research at RBGE
A world-wide network exists to coordinate phylogenetic work on green algae, and this includes RBGE. Selected taxa of green algae are isolated, taken into culture and DNA is extracted for sequence analysis. Current research focuses on morphologically very simple taxa whose placement in the green algal phylogenetic tree awaits detailed molecular phylogenetic analysis, for which strains are available from our collaborators and from culture collections.