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habitat types, community types, and plant communities in the Rocky Mountains. Gen. Tech. Rep. RM-123. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 105 p.

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Highlight: The present study was done to determine the effects of Artemisiu substances, both water-soluble and aromatic, on the germination of selected grassland species. Aqueous extracts of Artemisiu tridentutu litter inhibited germination of such species as Agropyron smithii, Euphorbia podperae, Hedeoma hispida, Parietaria pennsylvanica, and Thluspi arvense. Aqueous extracts of A. b-identutu and A. cana leaves inhibited germination of Achilles millefolium, Artemisia cana, A. tridentata, Bromus inermis, Chrysothamnus nauseosus, and Thhtspi arvense. Germination of these same six species was inhibited by volatile substances from leaves of A. tridentatu and A. cana. Aqueous extracts of leaves of Artemisiu bidentata, A. cana, A. absinthium, A. frigid& and A. dracunculusall inhibited germination of Haplopappus spinulosus and Thlaspi arvense. Germination of Echinacea pullida was inhibited by leaf extracts of all the Artemisius tested except A. drucunculus. Germination of Plantugoputugonica was inhibited by leaf extracts of only A. tridentata and A. dracunculus. Germination of Stipa viridula and S. corn&z was stimulated by leaf extracts of A. frigida and A. dracunculus. Aqueous leaf extracts of A. absinthium strongly inhibited germination of Stipu coma& but stimulated germination of Stipu viridula. Germination of certain species, such as Lepidium virginicum, Rumex crispus, and R. occidentalis, were not at all inhibited by leaf extracts of any Artemisius tested. Results of this experiment suggest possible influences of Artemisiu chemicals on species distributional patterns in Atiemisiu-dominated vegetation, though further studies are required to verify whether the influences are valid under field conditions. There has long been considerable interest in the toxic effects of plant extracts on other plants and the possible role of plant-plant interactions in the make-up of the plant community. In the case of Artemisia spp. early studies of Bode (1939) and Funke ( 1943) showed that A. absinthium leaves contained a sub-Authors are professor of biology and research assistant,