To test the hypothesis that eastern red cedar (Juniperus virginiana L.) is allelopathic, seedling establishment of five herbaceous prairie species was evaluated by growing seeds in soil collected beneath and adjacent to a stand of this tree species. While four species showed no significant effect, the germination of one species, finger coreopsis (Coreopsis palmata Nutt.), was significantly reduced. Since eastern red cedar is an early invader of unburned prairie, such an allelopathic effect, even on only a few species, is of particular concern in that it has the potential to hasten degradation of invaded prairie sites.
Stipe, Dan J. and Bragg, Thomas B., "Effect of Eastern Red Cedar on Seedling Establishment of Prairie Plants" (1989). Biology Faculty Proceedings & Presentations. 2.