The river appears in many colors, including yellow, green, blue, black, and especially red caused by the Macarenia clavigera (Podostemaceae) at the bottom of the river.
Due to its specialized aquatic morphology, it has often been grouped with other aquatic plants, such as the family Podostemaceae.
This genus seems to have relatively little in common with any other, and no affinity to the Podostemaceae except being aquatic; moved to its own family in the Cornales.