The life history of a monoecious species of Callithamnion (Rhodophyta, Ceramiaceae) in culture

Abstract
The life history of an alga, tentatively referred to Callithamnion baileyi Harv., has been examined in cultured isolates from Massachusetts, U.S.A. and Newfoundland, Canada. A sequence of monoecious gametophytes, carposporophytes and tetrasporophytes is described. Tetraspores invariably produced monoecious gametophytes, which were self fertile. The tetrasporophytes sometimes bore procarps and spermatangia, and a carposporophyte was observed on a tetrasporangial plant on a single occasion. Growth and fertility in culture were influenced by environmental conditions, particularly temperature. The origin of the multinucleate condition has been examined. The apical cell was invariably uninucleate, but the derivative cells were multinucleate. The Newfoundland isolates showed almost complete synchrony of nuclear division within each cell resulting in a geometric increase in the number of nuclei per cell. This synchrony was not observed in the Massachusetts isolates.

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