By Mark Debord – November 2023
Lake Anna is blessed with an abundant variety of native plant species. These plants are an important part of our lake ecosystem. They provide food and cover for pollinators, fish, waterfowl and aquatic invertebrate species. As important, they absorb nutrients that could otherwise feed harmful algae blooms (HABs).
American Water Willow (justicia americana) is one of the more common and noticeable of these aquatic plant species. It’s native to the area and common throughout Virginia. It usually grows in shallow water from a few inches to 1-2 feet deep. Stems can grow from 1-3 feet above water.
Water Willow is a perennial plant. It blooms from early Summer to early Fall. The blooms are usually white but will often have purple markings as well. The blooms attract a number of pollinators, especially native bees. Some of the smaller bugs will in turn attract dragonflies, an important natural mosquito predator.
In addition to seed dispersal, Water Willow spreads by rhizomes (through its underground root system). This is why you will often see Water Willow in colonies rather than stand-alone plants. Left undisturbed, these colonies can grow quite large.
Water Willow is sometimes mistaken for invasive weeds. However, given its widespread distribution around the lake, Water Willow is an important part of our efforts to reduce the nutrient load in the lake and thus reduce the HAB incidence. We want to encourage Water Willow growth where possible but recognize that it can interfere with access to docks or swimming areas. Before removing any Water Willow, make sure you are following Dominion’s requirements concerning aquatic vegetation. Lake Anna Reservoir and WHTF Vegetation Management & Herbicide/Pesticide Treatment Policy (azureedge.net)
Below are some resources if you want to learn more about this valuable native plant. If you have any questions, please contact Mark DeBord (firstname.lastname@example.org) or Lara Weatherholtz (email@example.com)
American Water Willow (usda.gov)
American Water-Willow (Justicia americana) · iNaturalist