The flowers of the Arrow Leaf Pondweed grow in dense clusters of 25 to 60 purplish to pale violet flowers, on a spike of 6 to 9 centimeters in length.

The spike sprouts from the side of the 0.7 to 1.2 meters high stem, some distance below the large arrow-shaped basal leaf on top.

The flowers have one blue anther and 5 anthers that are yellow. At 6 millimeter, the blue anther is slightly larger than the yellow ones, that are just 4 millimeter.