Photo by Kathy Rhodes.
Members of the Terrebonne Bird Club help collect air potato bulbils at a Nature Conservancy collection day.
Yams. Just that single word conjures up images of delectable dishes featuring the root crop for which Opelousas, Louisiana, is so well known. But don’t be fooled. What you thought all these years were yams are really not yams at all; they’re sweet potatoes.
There is, however, one type of yam abundant in Louisiana with no similarity to the sweet potato: Dioscorea bulbifera, a native of Africa and a member of the yam family. The common name for this invasive plant is the air potato or air potato vine.
Plant experts believe that the first air potato plant introduced to America was sent to a botanist in Orlando, Florida, in 1905 to be considered as a desirable ornamental and possible food crop. That edible species, Dioscorea alata, should not be confused with the inedible species of air potato vine that grows wild across Louisiana’s native bottomland hardwoods and wetlands and is easily identifiable by the big, heart-shaped leaves that sit opposite one another along the vine. The vines grow over bushes and up trees, reaching heights of seventy feet.
In June through September, Dioscorea bulbifera puts out little balls along its vines that greatly resemble small potatoes, which actually aren’t potatoes at all; rather, they are called bulbils. It is from these bulbils that the plants so readily spread. In the fall, as the vine dies back, the bulbils drop to the ground, where they sprout new vines in spring.
I first discovered this plant on my three acres in the marsh while walking the overgrown back section with my youngest son. We came upon these funny-looking potatoes and immediately dubbed them “dinosaur eggs.” By the following summer, the vines had blocked the sunlight from all the other plants below, choking out the native flora. Without using harmful herbicides, the best way to manage the plant’s growth is to remove the potatoes (bulbils). I had a brilliant idea. Handing each of my three sons a bucket, I offered them twenty-five cents for every “dinosaur egg” they brought me. It was a good investment; the vines are no longer a problem.
More recently, a bumper crop of air potato vines threatens to overtake the cheniere, or oak grove, on Grand Isle, a haven for migratory songbirds in the spring and a magnet for birdwatchers from across the country. The cheniere not only offers prime habitat for birds, it also offers prime growing conditions for the vines, which spiral up into the oaks, spread out into mats, and threaten native plant species.
In years past, the Nature Conservancy and local schools employed the same organic eradication technique that my sons and I used, collecting and destroying the bulbils. For the past few years, multiple groups, including members of Houma’s Terrebonne Bird Club, have also taken part in eradication programs. Although their combined efforts have resulted in the collection of several thousand pounds of bulbils, the vines continue to threaten the cheniere.
If you would like to help in this eradication effort, plan a day trip to Grand Isle this month in advance of the spring bird migration, which typically begins in April. You are encouraged to call the Grand Isle Nature Conservancy (985-787-3599) for more information about where to park, what to bring, and how to dispose of the air potatoes properly once they’ve been collected. You will be doing a great service to the chenier and the birds.
For more information about the conservancy and to read an article about previous air potato collections, please visit: http://goo.gl/Vxn9G3