Regional differences in hypericin and pseudohypericin concentrations and five morphological traits among Hypericum perforatum plants in the northwestern United States

Geographic differences among Hypericum perforatum L. plants in concentratio n of two hypericins and five morphological characteristics were analyzed in plants collected from four sites each in northern California and western M ontana and two sites in Oregon. Differences among regional collections of H . perforatum were assessed based on analysis of hypericin and pseudohyperic in concentration in floral, leaf, and stem tissue; light and dark leaf glan d density; leaf area; leaf length/width ratio; and stem height. Significant differences in morphological and biochemical traits were detected primaril y between samples collected from California and Montana. California samples had higher concentrations of hypericins, greater leaf gland density, large r leaves, and taller stems than those from Montana. Overall, Oregon samples did not consistently differentiate from those of Montana and California. S easonal differences in hypericins were analyzed in Oregon plants only. Mean floral concentration of pseudohypericin (0.29%) and hypericin (0.06%) were highest during anthesis coinciding with July and August sampling dates, wh ereas mean leaf concentrations (0.19 and 0.04%, respectively) were highest in August.