Conradina canescens

Williamson, G. B., N. H. Fischer, D. R. Richardson, and A. DE LA Pena, Chemical inhibition of fire-prone grasses by fire-sensitive shrub, Conradina canescens, J. Chem. Ecol., 15, 1567-1577 (1989). 

Two species produce phytotoxic monoterpenes Conradina canescens contains a mixture of monoterpenes, including 1,8-cineole, camphor, and bomeol (Williamson et al. 1989). Calamintha ashei contains a mixture of menthofuran monoterpenes (Tanrisever et al. 1988 Macias et al. 1989 Weidenhamer et al. 1994). Both species are mints, and presumably contain the terpenes in glandular tri-chomes on the leaf surface. Studies of the solubility of these compounds showed that their aqueous solubility is far in excess of their toxicity (Weidenhamer et al. 1993), which is necessary if these compounds are to be transported to the soil in aqueous solution by precipitation throughfall. 

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