Unveiling the osmophores of Philodendron (Araceae)

Philodendron, a species-rich genus of the arum family (Araceae), is thermogenic and produces strong inflorescence scents for pollinator attraction. However, the precise location of the scent-emitting tissue and its ultrastructure were hitherto unknown.

Gonçalves-Souza et al. show that the distal portion of both fertile and sterile staminate flowers function as osmophores in Philodendron adamantinum. The papillose epidermal cells of the distal portion of fertile stamens and staminodes are characterised by dense cytoplasm and large nuclei; the composition of organelles here is compatible with secretory activity, as indicated by the great number of mitochondria and plastids. In this portion, lipid droplets were observed, that were consumed concomitantly with the release of odour. These results indicate a functional link between thermogenesis and volatilisation of osmophore secretions to produce olfactory signals for attracting specialised beetle pollinators.