both the fruits and stems of heracleum maximum bartram, a common apiaceae found throughout northern north america, have been traditionally consumed as spice and food by american first nations and settlers. as both parts of the plant bear a distinctive scent, they have been submitted to volatile constituent extraction and their essential oils were studied by gc-fid and gc-ms. the fruits' oil was found to be mostly constituted of aliphatic esters, with octyl acetate (65.6%) as main constituent, while the stems yielded a generally terpenic oil, dominated by limonene (45.2%). these results were in line with data for other heracleum species, and constitute the first study of the volatile constituents of h. maximum. the observation of several octadecenyl acetates as trace compounds in the stems' oil allowed for the comprehensive identification of these uncommon and closely related isomers.