Our research focuses on the genus Amaranthus that includes over 60 species distributed globally. Several species are of economic importance as grain and vegetable crops. Many wild types display agriculturally desirable traits such as salt and drought tolerance, and also increased seed size. We have obtained accessions from the USDA Plant Introduction Station at Ames, Iowa. Our selection of samples includes a spectrum of all types including the threatened species Amaranthus pumilus, and the grain and wild types: A. caudatus, A. cruentus, A. dubius, A. flimbriatus, A. hybridus, A. hypochondriacus, A. rudis. Genetic diversity and phylogenetic relationships of some species have previously been investigated using isozymes, RAPDs, and chloroplast DNA. The goals of our research were to 1) generate a phylogeny of the chosen species using intersimple sequence repeats (ISSR), 2) determine the levels of intraspecific variation, and 3) to determine the ploidy levels of a portion of the studied Amaranth species. The ISSR data produced results similar to the RAPD data, but significantly more variability was detected. Multiple polyploid levels were detected within several species.

Key words: Amaranthaceae, polyploidy, seabeach amaranth