Historical overview of the genus Caulerpa

The distinctive habit of Caulerpa – a nonseptate siphonous thallus consisting of a creeping rhizome that produces tufts of colorless rhizoids downward and photosynthetic branches upward – was recognized as a generic character by Lamouroux in 1809. The uniqueness of this habit is supported by a suite of cytological, structural, and biochemical characters: the presence of trabeculae (struts of wall material), first demonstrated by Montagne in 1837; heteroplastidy (the presence of amyloplasts as well as chloroplasts), first demonstrated by Nägeli in 1844; holocarpic sexual reproduction involving anisogametes, first demonstrated by Dostál as well as by Schussnig in 1929; the presence of carotenoids (siphonaxanthin and siphonein) characteristic of siphonous green algae, first demonstrated by Strain in 1949; and the replacement of cellulose by xylan as a major wall constituent, first demonstrated by Mackie & Percival in 1959. The invasion of the Mediterranean, and subsequently other areas, by weedy strains of C. taxifolia and C. racemosa has stimulated research in numerous laboratories, resulting in hundreds of publications dealing with various aspects of biology in these species and other species of Caulerpa.