Abstract: Palmaria cultivars having a growth rate greater than wild type and known strains, particularly when cultured at temperatures greater than about 16° C., and specific embodiments of such cultivars, many of which had a rosette morphology, are described. Methods for isolating such cultivars and using the cultivars as a food source also are described. One embodiment of the method for isolating such cultivars comprised providing at least one sample of Palmaria and cultivating such sample in a container under environmental conditions to produce at least one Palmaria cultivar having a growth rate greater than wild type when cultured at temperatures greater than about 16° C. A particular embodiment of the method resulted in the isolation of Palmaria cultivars having a rosette morphology. Isolated Palmaria cultivars can be used as a food source for feeding organisms, such as humans.