Summary in English. / Bibliography: pages 146-169. / The biology, population dynamics, and the environmental tolerances (temperature and light) in laboratory culture, of the endemic intertidal South African fucoid Bifurcaria brassicaeformis (Kütz) Barton have been investigated. A general description is included of the morphology and anatomy, and comparisons made with that of other species in the genus. Studies on plants collected from contrasting habitats on the lowshore and from mid-shore pools revealed that while cortical thickness of vegetative uprights were similar for both habitats, medullary diameters were generally higher, corresponding to generally thicker uprights in the low-shore. Observations on the method of zygote attachment revealed that attachment of the species resembles that of the European Bifurcaria and Halidrys siliguosa which both also display delayed rhizoidal development and initially attach by means of a mucilage secretion of the zygote wall. Observations on receptacle anatomy revealed that size of conceptacles increase from the apex to the base of a receptacle.