Giant arrowhead plants are highly variable. The photographed specimen is typical of those found in the aquaria and water garden trade. Giant arrowhead has escaped cultivation and is found in the wild in several eastern, midwestern and far western states. Importation and trade is banned in some countries.

Sagittaria are monoecious; the pistillate (female) flowers are borne low on the inflorescence, staminate (male) flowers are uppermost. The photographed flowers are male. The fruit is a flattened winged achene with a single seed. Female flowers produce numerous seeds which have a high germination rate.

Sagittaria montevidensis began invading rice fields in southern Brazil in the 1980s. It was discovered at that time, that a herbicide-resistant biotype had developed within the populations found in agricultural areas.