The global distribution of wild tarragon (Artemisia dracunculus L.; Asteraceae) cytotypes with twenty-seven new records from North America

Artemisia dracunculus (wild or Russian tarragon), is a polymorphic, herbaceous perennial with a widespread distribution that spans western North America, Eastern Europe and most temperate of Asia. This wild relative of the culinary herb French tarragon has recently been the focus of a number of studies which have investigated its medicinal activity in type 2 diabetes bioassays. The species is documented as having from diploid to decaploid cytotypes and chemical variation has previously been shown to occur between cytotypes. To help focus germplasm collecting efforts for ongoing studies on variation of medicinal compounds within the species, a literature review of the geographical occurrences of cytotypes was conducted. This review revealed a lack of records from North America. In order to fill in this gap in the cytogeographic distribution, meiotic chromosome counts and flow cytometry were used to determine the ploidy level of 27 individuals from 16 different populations throughout the western United States. The results revealed distinct patterns of cytotype distribution. Both diploids and polyploid cytotypes were found in Eurasia, and the distributional range of each cytotype was found to be increasingly restricted as ploidy increased. For North America, even with the inclusion of many new records, only diploid populations were documented, with the exception of one hexaploid record from Arizona which was found in the literature.