Water Shield

Water Shield looks like a miniature lily pad and often indicates a fishing honey hole. Photo by Kenneth Boone

If you saw this plant growing in the water along the shoreline of a Lake Martin backwater, you may be tempted to call it a little lily pad.

You’d be wrong.

Water Shield does indeed share the roundish floating leaf structure of a water lily, but Monet didn’t paint it. And it wasn’t featured in fairy tales like The Frog Prince. And Water Shield doesn’t have the split leaf of a water lily.

Instead, Water Shield is a unique, under-the-radar, native aquatic plant that deserves to be better known.

Water Shield (also sometimes written Watershield or Water-Shield) is the common name for the species Brasenia schreberi. This is a one-of-a-kind plant, the only member of the Brasenia genus.

This plant is native to North America and is found all across the country except for the desert southwest. Water Shield is also found in all the Americas, the West Indies, eastern Asia, the Indian subcontinent, Africa and Australia.

It lives in slow moving, slightly acidic fresh water: ponds, lakes, swamps, streams and rivers. It is usually found along shorelines and in the shallows, but its stem can reach down as deep as 6 feet.

It is easy to identify because of three unique characteristics: its small, oval, bright green floating leaves; a reddish stem attached to the middle of the leaf’s underside; and a thick, transparent, slime covering all the submerged parts of this plant.

Water Shield leaves can be from1 to 2-1/2 inches wide and from 1 to 4-1/2 inches long. The leaves are primarily green on top and red-purple underneath.

The stem attaches to the center bottom of the leaf, like a mushroom stalk attaches to its cap. All the underwater parts are covered with a thick, clear jelly that protects the plant if the water recedes. This jelly may also discourage snails and aquatic plant eaters from munching on it.

Water Shield has an unusual flower, not because of the way it looks but because of the way it blooms. The flower is purple, small and not that noticeable, with three to four sepals (the outside protective part of the bud) that are purple on top and green underneath. It has four purple petals that are longer and thinner than the sepals.

What makes these flowers unique is that they emerge from the water twice over a two-day blooming period, once functioning as a female and once as a male.

On the first day, the bud rises above the water and the sepals and petals open, showing the pistils, or the female organs of the flower, which gather in pollen. That night, the flower stalk falls over and the flower goes underwater. On the second day, the stalk lifts the flower above the water again, but this time, the pistils are retracted and the male organ, called the stamens, lengthens and the flower’s anthers open and release their pollen. The flower then drops back into the water where a leathery, nut-like fruit with one or two seeds develops. Waterfowl eat the fruit, and the seeds are distributed through their droppings.

Water Shield can also reproduce by sending out rhizomes from its “mother root,” which creates many plants in a tightly packed colony.

Although you wouldn’t think a slimy aquatic weed is good to eat, Water Shield is actually cultivated as a food crop in Asia. In Japan, it is sold in grocery stores as “junsai” and used in salads and miso soup. In China, it is known as “chun chai” and is the star of a Hanzhou dish called West Lake Water Shield Soup.

Native Americans ate the rhizomes and young leaves.

According to the forager website Eat The Weeds, the young leaves and stems of Water Shield can be eaten raw or cooked. Its roots must be peeled, or they are too bitter to eat; however, once peeled, they can be boiled and eaten or dried and ground into flour. The site says the best time to collect Water Shield roots is the cooler months from autumn to spring.

Because Water Shield can grow in dense colonies, it is sometimes considered a nuisance plant, causing problems for swimmers and boaters that can’t easily push through it; however, fishermen often prize Water Shield colonies because they provide good habitat for aquatic life and usually create a fishing honey hole.

Some information for this article came from U.S. Forest Service, www.eattheweeds.com, www.thewildclassroom.com, and Loyola University Center for Environmental Communications.