Acorus calamus L. (Sweetflag, Acoraceae) is a perennial aquatic macrophyte with a widespread global distribution. The plant is locally abundant in riparian areas of the Northeastern United States and Canada. Shoots arise from a geophytic rhizome, which reproduces clonally. The rhizome grows sympodially and ramifies by means of terminal and lateral buds, respectively. All ramets have potential for individual growth as independent physiological units though they remain attached to the genet. The rhizome has essential oils with medicinal, and pesticidal properties and is important to several ethnoharmacoepias. Despite its importance, little is known about abiotic factors influencing rhizome biomass and structure among A. calamus populations. Ten rhizomes were gathered randomly from each of eleven populations of A. calamus in southeast Ohio. Soil samples were also gathered at population sites and analyzed for texture, pH, moisture, organic matter and inorganic ions (N, P, K, Al, Ca and Mg). The length and number of leaf scars was noted for each rhizome. Rhizomes were dried at 80o C to obtain dry weight. One-way analysis of variance indicated significant differences in rhizome weight (F = 3.34, p < 0.001), rhizome length (F = 2.72, p < 0.01) and number of leaf scars (F = 4.54, p < 0.001) among populations. Spearman’s rank correlation indicated that rhizome biomass is correlated with Ca (r = 0.58, p < 0.1), Mg (r = 0.53, p < 0.1) and pH (r = 0.55, p < 0.1). Rhizome length is also correlated with Ca (r = 0.78, p < 0.1), Mg (r = 0.58, p < 0.1) and pH (r = 0.58, p < 0.1). The findings indicate that biomass and length of A. calamus rhizome may be influenced by availability of soil nutrients. Microenvironment may be an important consideration for sustainable harvest and conservation efforts.

Key words: Acorus calamus, edaphic factors, rhizome, southeastern Ohio