American Lotus, Nelumbo lutea: locally known as graine à voler

Wednesday, September 30, 2009

Nature Notes
by Bob Thomas

From nanotechnology to good eats, our indigenous American lotus (Nelumbo lutea) is a fascinating and culturally important plant. A member of the Nelumonaceae that occurs along sluggish waterways in most of the eastern United States, Central America, Colombia and the West Indies, it is also variously called water lotus, yellow lotus, water chinquapin, duck acorns (the seeds look like acorns sans their caps), pond nuts, and more. In coastal Louisiana, we call them Cajun peanuts or graine à voler (grain ah volay).

Watch rainwater hitting the upper surfaces of lotus leaves and you will see it form droplets that may coalesce into puddles (the "lotus effect"). The leaves repel water which beads up on the surface or fills the cup formed when the leaves extend above the water's surface. According to Casey LeBlanc, Des Allemands native who has grown up in the surrounding marshes and swamps, local fishermen use fresh rainfall caught by the lotus leaves as a safe source of drinking water.

The leaves have a waxy surface that slightly attracts water (forming progressively larger droplets) and nanoscale grooves and bumps that cause water to glide about on the leaf surface, thus cleaning the surface of the leaf of soil, bacteria and the like. Nanotechnology involves discovering how things happen in nature at the nanometer scale (1 nanometer [nm] = 1 billionth of a meter) and duplicating those characteristics in human-made applications. Scientists around the world are replicating the ultra-structure of lotus leaves and are applying the repellent system to a range of applications such as coating hulls of ships to protecting suspension cables. Medical scientists are even using their knowledge of the lotus effect for diagnosing certain forms of cancer and creating vascular and bile duct stents that prevent fouling agents from adhering to their surfaces. GE's Global Research Center is experimenting with "hydrophobic nano-coating" paints for airplanes that may repel ice, thus eliminating the need to delay flights requiring the application of de-icing fluids.

Lotus leaves and flowers grow from rhizomes (laterally growing roots) anchored in the soil. The leaves are perfectly round, smooth on top and ribbed on the lower surface, grow at the tip of a petiole (stem) that may be six feet long, and may float flat on the water surface or become cup-shaped as they extend into the air. Their pleasantly fragrant white to pale yellow flowers are the largest native flower in the United States and they also grow at the tip of a stem that may be six feet long.

Lotus seedpods are cone-shaped with the seeds visible as bumps on the flat upper surface. Oddly, they look like shower heads. The pods are yellow when developing in the center of the flower, green when the petals and sepals fall, and brown as the pod dries and the seeds are dropped. The spent pods are very popular in dry floral arrangements and are available in most flower shops.

I have always heard that the seeds are shot out of the pods, thus the name graine à voler (flying seeds). Indeed, when the seeds are ready to leave the pod, they become loose and rattle about in their cavities. Joey Fonseca, another Des Allemands marsh expert, agrees that when the seeds are ready to drop, the pod dips over and the seeds simply fall into the water.

Native Americans seasonally relied on lotus in their diets. They baked the rhizomes like sweet potatoes, steamed or boiled the unrolled new leaves, ate immature seeds raw, and roasted mature seeds or ground their contents into a starchy flower. It is believed that the original distribution of American lotus in the United States was restricted to the area of today's southeastern states. The plants were probably transported north by Native Americans who either trekked south to harvest the plant or obtained it by trading.

Casey LeBlanc loves to pull over in his air boat, nibble on fresh Cajun peanuts, and soak in the ambiance provided by the surrounding natural wetlands and their inhabitants. Like all good Louisianans, Casey has a number of recipes for graine à voler that are quite tasty.

Although American lotuses are fragrant, beautiful, and interesting components of our coastal freshwater wetlands, they often grow so thickly that they become a nuisance, unless you like to eat them!

                                    

A typical "lotus marsh" that includes leaves                              From late spring to late summer, lotuses
floating on the water surface and extending                             flower and prosper. They may become very
into the air. The "trash" on the leaves is                                   thick and difficult for humans to navigate.
Salvinia, a troublesome invasive species                                  Photo by Bob Thomas.
that usually floats on the water.
Photo by Bob Thomas.

                                  

Lotus seedpods. The green one in the front                              Note the clean, clear rainwater puddled
has ripe seeds (a little too ripe to eat), and                              on this healthy lotus leaf.
the brown one in the back is equally ripe,                                Photo by Bob Thomas.
but the pod is brown and dry. A dense lotus
marsh can produce 85,000 seeds per acre.
Photo by Bob Thomas.

                                 

A tasty Cajun peanut about to be plucked                               Casey LeBlanc, guide extraordinaire and
for a snack. The soft shell is removed and                               expert on the marshes of Lake Des
the contents are eaten. Very nice!                                          Allemands.
Photo by Bob Thomas.                                                       Photo by Bob Thomas.