plants produce volatile compounds that can be phytotoxic. these compounds are present in the asteraceae shrub baccharis psiadioides less. essential oil. therefore, we assessed effects of b. psiadioides essential oil on several phases of arabidopsis thaliana (l.) heynh. life cycle. essential oil chemical composition was verified by gas chromatography. seeds and seedlings were exposed to volatiles in plates with agar medium whereas juveniles and adults were exposed inside glass chambers in soil. oil chemical composition revealed monoterpene hydrocarbons as the most abundant chemical category and -pinene was the major compound (44.65%). germination and early growth were reduced by volatiles. most evaluated parameters on juvenile and adult plants were not affected, but growth of juveniles decreased. we conclude that early phases of plant development were sensitive to the volatile's exposure.