The Life History of the Brown Alga Splachnidium rugosum

Abstract

The life history of the brown alga Splachnidium rugosum (L.) Grev. has been studied in culture. Biflagellate zoospores produced in unilocular sporangia borne on the macroscopic plant, give rise, without fusing, to microscopic filamentous thalli. Plurilocular sporangia formed on these thalli liberate zooids which develop, probably after fusing, into similar but more robust filamentous thalli. The latter form plurilocular sporangia and also give rise directly to macroscopic Splachnidium plants. These observations are consistent with an alternation of heteromorphic generations and are compared with field observations made in Victoria, where similar filamentous stages have been observed. An axile stellate chromatophore is characteristic of all phases of the life history. The occasional occurrence of periclinal cell divisions leads to a discussion of the affinities of the genus.