NPK-contents of macrophytes from the Mediterranean Morocco. This work presents an assessment of NPK (nitrogen, phosphorus and potassium) -contents of the main macrophytes from the Mediterranean Morocco. Lemna gibba, leaves of Salix purpurea and reproductive parts of Tamarix africana present a high nitrogen content; while Lemna gibba, underground parts of Sparganium erectum and reproductive parts of Vitex agnus-castus have a high phosphorus one.