Phenolic contents of submerged, emergent and floating leaves of aquatic and semi‐aquatic macrophyte species: why do they differ?

The phenolic content of leaves of 40 aquatic and semi‐aquatic plant species, collected from stands distributed over the Netherlands was investigated. Species with submerged leaves showed a significantly lower phenolic content than species with emergent or floating leaves; the latter two showing no significant differences. Possible explanations for the observed differences are discussed in relation to defence strategies.