Flowering and pollination of Philodendron melinonii (Araceae) in French Guiana

The pollination ecology of Philodendron melinonii was studied at two locati ons in French Guiana. Inflorescences of P. melinonii were regularly visited by Cyclocephala colasi, a scarab beetle also found in inflorescences of P. solimoesense in the same area. The flowering cycle lasted two days and the inflorescence exhibited features typical for beetle pollination (e.g,, flo ral chamber, food rewards, flower heating). The flowering process is well s ynchronized with the night activity of Cyclocephala visitors. The spadix te mperature was measured during the entire flowering cycle in the field in Fr ench Guiana and in greenhouse conditions at the Montreal Botanical Garden. Both measurements gave a similar temperature pattern with a two hour delay at the Botanical Garden. The spadix warmed up twice during the flowering pe riod and its temperature was not significantly different from that of ambie nt air between the two peaks, These two temperature peaks are also well syn chronized with the arrival and departure of the beetles on two consecutive nights.