Pollination ecology of Symplocarpus foetidus (Araceae) in a seasonally flooded bog in Québec, Canada

ABSTRACT

The pollination ecology of Symplocarpus foetidus (L.) W. Salisbury was studied in a seasonally forested flooded bog in Québec (Canada) in 2008 and 2009. The protogynous anthesis duration ranged from 15 to 20 days with, chronologically, a female phase of about 5 days, a bisexual phase of 2 days, and a male phase of 9 days. The spadix temperature differences with ambient air were higher during the female phase (mean: 13.6°C) than during the bisexual and male phases (mean: 4.5°C). The air inside the floral chamber was warmed by the heating spadix, particularly during the female phase (~6°C warmer than ambient air). High temperatures were maintained through nighttime during the female phase, whereas they occurred only during the daytime during the bisexual and male phases. The average natural fruit and seed sets were relatively low (18.2% and 14%), and the fruit set varied between years (13% in 2008 vs. 31% in 2009). Since spontaneous self-pollination is a rare reproductive event, sexual reproduction in Symplocarpus foetidus relies mainly on insect cross-pollination. Pollination is probably generalist considering the large variety of Coleoptera and Diptera families attracted to the plant, such as Chironomidae, Sphaeroceridae, Mycetophilidae, Phoridae, Drosophilidae, Chloropidae, and Anthomyiidae. Since many different insect types visit the inflorescences, it is unclear whether this pollination system is a deceptive interaction (its unpleasant floral scent is typical of other deceptive Araceae), a breeding site mutualism (developing larvae have been observed on the inflorescences), or a combination of the two.

KEYWORDS:

• Anthesis
• flowering sequence
• thermogenesis
• visiting insects
• fruiting success

Acknowledgments

The authors wish to thank Léa Bouttier for the use of her photographs in Figure 1. This study was funded in part by a grant from “Les Amis du Jardin Botanique de Montréal” (To D.B., S.P., M.G.), and a grant from the Natural Sciences and Engineering Research Council of Canada (To D.B.). The authors also wish to thank Dr Marion Chartier and an anonymous reviewer for their constructive suggestions for the manuscript. The authors thank Marilyne Tremblay Coutu for linguistic revision and proofreading.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

Isabelle Barriault: field work, laboratory measures, insect identifications, and drafting of manuscript.

Denis Barabé: study conception and drafting of manuscript.

Louise Cloutier: insect identifications and drafting of manuscript.

Stéphanie Pellerin: fieldwork and drafting of manuscript.

Marc Gibernau: study conception, data analyses and drafting of manuscript.