P ickerelweed typically grows to about two to three feet tall. Its leaves are large, up to five inches wide, and are usually twice as long. Leaf shapes are variable, but are usually lance-shaped. The easiest way to recognize pickerelweed is by its spike of violet-blue flowers . Sometimes the flowers are white.
Illinois pondweed grows equally well in swift-flowing rivers or quiet lake margins.
The submersed leaves are about the same size, but are more lance-shaped. Submersed leaves have pointed tips and pointed bases. Illinois pondweed's greenish flowers are on spikes that are one to three inches long. Other Pondweeds T here are about 80 species of pondweeds in the world. They occur in a variety of aquatic habitats.