A cytological study of intraspecific variation in Ceratopteris thalictroides

Abstract

A cytological study of meiotic pairing behavior in intraspecific hybrids was undertaken utilizing seven different collections of Ceratopteris thalictroides. Two mutant gametophyte stocks with nonfunctional spermatozoids were utilized to facilitate the synthesis of intraspecific hybrids. Low levels of univalent and quadrivalent formation were found in most of the hybrids, indicating that some structural differences existed, but major pairing homologies were still evident. The fertility of hybrids ranged from 10 to 75% spore germination. One collection, from Hawaii, showed high levels of univalent formation and very low spore viability. In that this stock is both biologically and morphologically distinct, it should be given taxonomic recognition. The study, in general, is in agreement with the most recent taxonomic treatment of Ceratopteris in that it shows a significant amount of cytological variation within the polymorphic species C. thalictroides.