Spadix temperature was measured in three species of Philodendron: P. acutatum, P. pedatum and P. solimoesense.
These species showed two different patterns of spadix temperature during their flowering cycle. In P. acutatum and P. pedatum (subgenus Philodendron), the spadix warmed up twice during the beginning of each flowering night with a temperature not significantly different from that of ambient air between the two peaks.
In P. solimoesense (subgenus Meconostigma), the spadix temperature rose up to 14oC above that of ambient air during the first night, then it progressively cooled down but remained 3-6oC above ambient air temperature.
We propose that the heat production and the spadix temperature patterns observed may reflect different physiological processes and have a taxonomic significance in the genus Philodendron.