THE FLORAL ODOR OF ARUM-MACULATUM

Non-invasive headspace analyses of the odour produced by inflorescences of Arum maculatum L. still attached to plants growing wild in southern England revealed that the major components were 2-heptanone, indole (each comprising 8-23% of the volatiles) and germacrene B (10-14%). p-Cresol (0.2-6%) was also a notable odorous component amongst the 56 compounds present, however, simple amines, reported in previous invasive studies, could not he detected. Although the major odorous organ was the spadix appendix, microheadspace analyses revealed that the germacrene B originated entirely within the spathe chamber, probably from the fertile portion of the spadix. The main pollinator was confirmed as females of Psychoda phalaenoides L. and a comparison of the inflorescence volatiles with those produced by cow dung, the normal breeding microhabitat of the pollinator, identified p-cresol as the major common component.