An examination of the phytotoxicity of the water shield,Brasenia schreberi.

Antialgal, antibacterial, and allelopathic properties of the submersed, aquatic, dicotyledonous water shield,Brasenia schreberi Gmelin (Cabombaceae), were examined. Extracts ofB. schreberi were found to inhibit the eukaryotic alga,Chlorella pyrenoidosa, and the prokaryotic alga,Anabena flosaqua, as well as nine different bacteria. Lettuce seedling bioassay showedB. schreberi to be allelopathic. These phytotoxic properties probably contribute to the observed dominance ofB. schreberi in aquatic environments and also make it a promising candidate for allelopathic plant management of aquatic weeds.