ABSTRACT:

The pollination success of the dead horse arum, Helicodiceros muscivorus, was studied in one Corsican population. This aroid species is pollinated by deception, attracting blowflies by mimicking the floral volatiles emitted by mammal cadavers. The reproductive individuals were taller and larger than non-reproductive ones, indicating that the plant vigor and thus the available amount of resources is an important factor in the production of an inflorescence. The reproductive success of the dead horse arum increased with the size of the inflorescence, as judged by a positive linear correlation between the appendix length and the total number of flies trapped within the floral chamber. Larger inflorescences had a longer appendix and thus a better probability to attract and dupe pollinating flies. The absence of correlation between floral sex-ratio and the spadix size indicated that there was no expression of the size-advantage model in H. muscivorus apparent in some other Araceae. The most probable explanation is that pollination efficiency is high because of low diversity and high abundance of pollinating insects.