Morphological and chemical variations of sweet flag (Acorus calamus L.) in the Czech and Finnish gene bank collection

The aim of this study was to analyze both the morphological and chemical characteristics of Acorus calamus plants collected from the natural sites in the Czech Republic and to compare them to the sweet flags growing in Finland, Slovenia and Canada, which are concentrated in the Gene Bank collections in Finland. The sweet flags of Finnish, Slovenian and Czech origin were found to be phenotypically and chemically very similar. They all represent the European triploid type of Acorus calamus var. calamus. The average essential oil content was established at the value of 1.50% of dry material in Finland and 1.91% in the Czech Republic. This amount is not sufficient according to the Czech norm for Radix calami quality (minimal amount is 2%) but the content of carcinogen P-asarone, which was established at 9-21% in the essential oil in all the analyzed sweet flags, did not exceed the maximal recommended value 0.5% of dry drug mass.