Field and cultural observations on the growth and reproduction ofPolysiphonia denudatafrom Texas

Abstract

The life history of an isolate of Polysiphonia denudata (Dillw.) Kütz. from Texas is shown by means of cultural studies to be of the Polysiphonia-type (a sequence of gametophytic, carposporophytic and tetrasporophytic phases in which the former and latter are morphologically similar). The effects of light intensity and temperature on the isolate have been investigated by a cross-gradient culture apparatus; a series of incubators was used to investigate the effects of variations in daylength on the growth and reproduction of the species. Seasonal observations were conducted on growth and reproduction of the species in nature and an attempt is made to explain the observed distribution of the species on the basis of the cultural study.