Éditeur(s) : HAL CCSD
Résumé : International audience
Philodendron acutatum (Araceae) is a hemiepiphyte common to the Atlantic Forest of northeastern Brazil. In two localities, we studied the species’ breeding system and associations with flower-visiting insects, along with an analysis of its floral scent composition. The fruit set of self-incompatible P. acutatum was high, more than 90%, and inflorescences were exclusively pollinated by one species of scarab beetle, Cyclocephala celata (Scarabaeidae, Dynastinae). Pollinators are drawn toward the inflorescences at dusk by strong floral fragrancesgiven off during the female phase of anthesis, along with endogenous heating of the spadix, whose temperatures were recorded at more than 11C above ambient air. Two other species of flower-visiting Cyclocephala were also consistently recovered in blacklight trappings during the flowering period of P. acutatum. The fact that only C. celata was found in association with P. acutatum suggests a local reproductivedependence of the plant to this scarab beetle species. Dihydro-b-ionone and 2-hydroxy-5-methyl-3-hexanone, a rare volatile molecule so far unreported as a floral compound, together accounted for more than 97% of the unique scent composition of P. acutatum and might be involved in specific attraction of C. celata.
International Journal of Plant Sciences

hal-01094225
https://hal-agroparistech.archives-ouvertes.fr/hal-01094225
DOI : 10.1086/654846

Éditeur(s) : HAL CCSD International Aroid Society
Résumé : International audience
ISSN: 0197-4033

hal-01095862
https://hal-agroparistech.archives-ouvertes.fr/hal-01095862

Éditeur(s) : HAL CCSD Museum Nationale d'Histoire Naturelle Paris
Résumé : International audience
Comparative study of heat production in some Araceae. The thermogenetic cycle of the inflorescences is compared in the genera Anubias, Cercestis, Dieffenbachia, Homalomena and Philodendron. The genera Philodendron, Anubias and Homalomena have a thermogenetic cycle characterized by the production of two peaks of heat. In Dieffenbachia and Cercestis the cycle is characterized by the presence of a single peak appearing during the first day of the floral cycle. Differences between these two thermogenetic patternsare linked with pollination mecanisms.
Comparaison du cycle thermogénétique des inflorescences dans les genres Anubias, Cercestis, Dieffenbachia, Homalomena et Philodendron. Les genres Philodendron, Anubias et Homalomena ont un cycle thermogénétique caractérisé par la présence de deux pics de chaleur sans différence de temperature entre les deux événements. Dans les genres Dieffenbachia et Cercestis le cycle thermogénétique est caractérisé par la présence d’un seul pic de chaleur qui apparaît le premier jour du cycle floral. Les différences entre les deux types de cycles thermogénétiques sont liées aux mécanismes de pollinisation.
ISSN: 1280-8571

hal-01202740
https://hal.archives-ouvertes.fr/hal-01202740

Éditeur(s) : HAL CCSD National Research Council Canada
Résumé : International audience
In French Guiana, inflorescences of Philodendron squamiferum Poepp. (Araceae) were regularly visited by the scarab beetle Cyclocephala simulatrix Hölne and (Scarabaeidae, Coleoptera) occasionally by Cyclocephala tylifera Hölne. The flowering cycle lasted 2 days, and the protogynous inflorescence exhibited features typical of beetle pollination (floral chamber, food rewards, flower heating). The spadix temperature was measured during the entire flowering cycle in French Guiana and at the Montreal Botanical Garden. Both sets of measurements gave a similar temperature pattern. The spadix warmed up twice at the beginning of each evening with no notable heat production between the two peaks. These two temperature peaks were well synchronized with the arrival and departure of beetles
ISSN: 0008-4026

hal-01202724
https://hal.archives-ouvertes.fr/hal-01202724