Flowering period, thermogenesis, and pattern of visiting insects in Arisaema triphyllum (Araceae) in Quebec

Jack-in-the-Pulpit (Arisaema triphyllum (L.) Torr.) is a perennial forest herb of southern Canada and the eastern United States. The flowering periods of male and female inflorescences in relation to the temperature of the inflorescence and the activity pattern of visiting insects were studied in one population in western Montreal Island (Quebec, Canada). The flowering period of A. triphyllum was long (20 d in male and female plants), which is unusual in temperate Aroideae. This floral trait could have evolved secondarily as an adaptation to increase pollination efficiency under highly variable weather conditions at high latitude. In male and female plants, no significant temperature increase of the appendix was recorded. The warming effect of sunlight during the day could be sufficient for the emission of the attractive odour. Two Dipteran families, the Mycetophilidae and the Cecidomyiidae, were the most frequent insect visitors of A. triphyllum. Our observations showed that odour production is linked with the pollination activity beginning with insect visits.