Willow Grass
Riverdave's Journal
This essay appeared in the Durham Herald-Sun on 8/1/96

Expectations are sometimes too high for paddlers hoping to voyage down the Eno River during the summer. I often find friends and relatives anxiously waiting at West Point Park to pick up paddlers coming downstream from Orange County. These ill-conceived expeditions did not take into account that it is healthy and normal for a Piedmont river to run low in the summer. The paddlers usually arrive after dark, tired and weary, having hauled boats over countless rocks and through an almost endless sea of summer willow grass.

What at first glance may appear to be an invasive aquatic plant, often stretching completely across the river channel, is actually an extremely important component of the native ecology of a Piedmont river. In the summer there are sections of the Eno River where no water can be seen at all, as the river quietly flows entirely hidden beneath a low canopy of willow grass foliage.

Here is how it works. Around the first of May, as the early spring rainy season ends, the young shoots of the willow grass begin to emerge from their roots on the bottom of the river. As the water level drops, this plant will poke its leaves above the surface to a height of about two feet. Early spring's deep flowing channel of water eventually becomes a shallow trickle of only a few inches under willow grass as we move into the warmer and drier months of the year.

This plant, Justicia americanus, produces a flower by the first of July that is similar to our familiar cultivated Mediterranean species of Acanthus to which it is related. Atop the summer sea of willow grass will be a myriad of inch-long, purple and white symmetrical flowers, each one divided into two equal parts.

This colonial plant spreads across rocky streams and shallow rivers by means of rhizomes - horizontal, underground stems. The rhizomes produce shoots with slender, paired, four inch leaves that remind us of the leaves of the willow tree, therefore providing the basis for the common name of willow grass.

In North Carolina willow grass is most abundant in the lower Piedmont, but its range extends from Ontario to Wisconsin and south to Texas and Georgia. Six other species of Justicia are native to the eastern United States becoming most concentrated in Florida. The Acanthus family is largely a tropical family of plants with over 2500 species worldwide.

Further south into the tropics one may meet another relative of willow grass, Justicia pectoralis. This species contains psychoactive properties with strong aphrodisiac and hallucinogenic powers. This plant is used as a snuff by shamans in their ceremonial practices in the upper Orinoco River region of Venezuela. 

Willow grass habitat is important to the ecology of a Piedmont river in that it performs the task equivalent to that of the coastal marsh estuary. Many newly hatched fish, snakes, amphibians and other aquatic animals need a sheltered and protected place to grow before they have to face the major predators of the river such as the largemouth bass and other members of the sunfish family.

These predators remain in deep pools along the margins of the willow grass. They await the careless young of other species who would dare to venture momentarily from the shelter of the willow grass into deeper water. To wade or snorkel through the summer canopy of willow grass is a marvelous way to explore the life forms of a healthy Piedmont river.

By late fall the foliage of the willow grass begins to look ragged. Its stems weaken, drop leaves and eventually winter rains produce freshets that mat down what is left of its summer glory back to the substrate of the river. One very important cycle of the river is completed. What had once been a launching platform for daring dragonflies and darting damselflies and a refuge for frightened fry and fair-weather frogs, has now retreated to allow the yearly winter flooding and over wash of the river to return once again ...