Acorus calamus L. (also known as sweet flag) is a perennial, aromatic herb, one form of which is native to marshy regions in northern temperature zones of Europe, where it grows wild along the banks of rivers and ponds, as well as along the edges of swamps. This is the triploid, or European, form of A. calamus var. calamus. A diploid form, which can be found in Canada and the United States, is A. calamus var. americanus (Raf.) Wulff, while a tetraploid form, which is native to Central Asia, India and Himalayan countries, is A. calamus var. angustata Engl. (syn. A. calamus var. angustatus Bess.).
Ploidy refers to the number of sets of chromosomes found in the biological cells’ nucleus. The base plants are diploids, which contain two homologous copies of each of the chromosomes from the male and female. Triploids contain three sets of chromosomes and are generally sterile. Tetraploids contain four sets of chromosomes and, as such, grow more vigorously than triploids or diploids.
Stahl and Keller (1981) reported that the oil content of diploid rhizomes of Canadian and U.S. origins was 4.7–6.0%, the oil content of triploid European rhizomes was 1.7–4.0% and the tetraploid Asian rhizomes possessed an oil content of 4.8–8.7%.