Studies on Gracilaria. I. Morphological and Anatomical Variation in Samples from the Lower Gulf of St. Lawrence and New England

Abstract

Samples of Gracilaria collected from 6 populations in the lower Gulf of St. Lawrence [Canada] and New England [USA] were analyzed with respect to 7 vegetative criteria of taxonomic importance in the genus. There was significant interpopulation variation, but variation ranges of the samples overlapped to a considerable extent. The absence of discontinuities in the variation patterns suggests that only 1 taxonomic species was represented in the populations. Seasonal variation in morphology and anatomy occurred and must be taken into account in any taxonomic treatment of Gracilaria.