Phytotoxicity of constituents of glandular trichomes and the leaf surface of camphorweed, Heterotheca subaxillaris

Borneol (1), phytotoxic calamenene-type sesquiterpenes (2-5, 9-11) and methylated flavones (12-15) were isolated from the dichloromethane rinsate of camphorweed aerial tissues. The strongest plant growth inhibitor against Agrostis stolonifera and Lactuca sativa seedlings, as wells as duckweed (Lemna pausicostata), was 2-methoxy-calamenene-14-carboxylic acid (2).