Sunday, September 11, 2011

Groundnut - Apios americana

Out of all of the alternative staple crops, groundnut is one of my favorite. What excites me most about groundnut is the fact that it is both a legume and it's grown for its starchy tuber. It combines the nitrogen fixing capabilities of legumes with the advantages of starch-producing tubers, and in fact, has several additional health benefits on top of that.
It has a protein content that is quite high, at around 15%. A commonly cited figure says it's about three times that of potato. In combination with grains, it can provide proteins with balanced levels of amino acids, vital for the adequate use of dietary protein. In addition, studies on rats fed a diet of groundnuts has shown a decrease in blood pressure and cholesterol levels. Some varieties of groundnut also contain substances known as isoflavones, which have anti-cancer effects. One nutritional downside that is easily fixed are proteases - protein dissolving enzymes - found in the tubers. Simply cooking the tubers deactivates these enzymes and makes them safe to eat, although I'm not sure you'd want to eat them raw anyway. Baked, they are quite delicious and from my experience, they taste like a peanut flavored potato.

Apart from it's nutritional benefits, why would you want to grow groundnuts in Western Washington? Well, on top of it being a leguminous root crop that could produce its own fertility, the plant can tolerate very wet conditions. In its native habitat, groundnut grows in bogs. Here in Western Washington, soil conditions are often quite wet for a good part of the year, so tolerance to bogginess is a plus. It can also endure quite acidic soil pH's, which is another advantage as acidic soils tend to be the rule for Western Washington.

    For an alternative staple crop, groundnut also has a fairly interesting history. It was the major staple tuber for Native Americans that lived in its range (Eastern North America), and when the Pilgrims settled in Plymouth and found themselves having food shortages, groundnut came to their rescue. It was actually cultivated by colonists for a while, and later, it was grown after the potato famine in Ireland as a potential replacement crop. Some say the plant made its way to Japan where its still cultivated, although others speculate the plant grown there is another Apios species.

    More recently, attempts were made to domesticate groundnut in the 80's and 90's by Professor Bill Blackmon at Louisiana State University and many improved varieties were produced. However, funding was cut from the program.

    Many varieties can still be found from that program, and I had thought many were lost. However, the forty strains of groundnut that Professor Blackmon took with him when he left the program are still alive and around at Mountain State University. This past fall, I planted eight of these varieties I received from Dr. Mario Morales at MSU, who sent them to me to plant in a field trial at the Organic Farm at the Evergreen State College in Olympia. Unfortunately, being on the other side of the state, it's hard to know how each varieties are doing, but hopefully, I'll find more out when I travel across the Cascades in a few weeks.

    So how do you grow groundnut? And where can you get it?

    Groundnut is best grown on trellises, as it is a vining plant. Tubers of the plant are planted in the spring or preceding fall, and then harvested that fall or the following fall. Plants grown one year will produce small tubers in northern latitudes, while growing two years will produce a more substantial yield.

    As a legume, it needs to be inoculated by the correct nitrogen-fixing bacteria. Luckily, it shares the same bacteria as does soybeans and cowpeas, and innoculant can be gotten relatively easily.

    Tubers can be found at a few places. Oikos Tree Crops out of Michigan sells several varieties of groundnuts. Seed Savers Exchange is another good source for a few different types of groundnuts.

    This is my second year growing groundnut. The first year, the plants grew fairly well, definitely filling the trellises. I had one LSU domesticated variety and another variety I got from Europe that was more adapted to northernly latitudes. The LSU variety did not flower (something I think those varieties may have more trouble with as their adapted to warmer climates), though the variety from Europe did.

    One challenge with growing groundnut and breeding it in the Pacific Northwest will be in making crosses. Getting LSU varieties to flower here may be challenging or outright impossible, and these would be the varieties one would want to cross. Wild, northern types of groundnut from New England would be great material to cross with as well, tough unfortunately many plants in these populations are sterile triploids. However, diploids from as north as Connecticut do exist. Obtaining plants from these populations would be a good first step in breeding groundnut varieties for the PNW.

    This is what the plants look like the second year; they shot up rather quickly, and I can understand how yields could be much higher the second year. The plants are much more vigorous, though I did notice a few I had planted didn't come up the second year. I'm not sure what caused that; cold damage seems unlikely as this species is as found as far north as Quebec.

    Overall, I'd say groundnut is a species with great potential as a future important staple crop. I can only wonder what the crop would be today had the domestication program at LSU continued. For now though, small experimental gardeners like us can safeguard the improved varieties developed in these programs, as well as experiment with wild varieties. For Cascadian groundnut enthusiasts, I'd say our best chance lies in locating diploid groundnut varieties in New England that would flower in our climate. Then we could begin crossing varieties and selecting for types that do best in our environment. Or, if you have a friend further south, perhaps crosses between cold adapted diploid types from New England could be made with LSU varieties, as the weather would be warm enough for those varieties to flower and set seed.




  1. Awesome! I would to try some of those LSU varieties! Seed Savers does not have any currently listed on their website. Do you know who I might contact to purchase some of the LSU varieties? my email is dolomite792(at)yahoo(dot)ca. I live in Arizona and would love to try some of these out.

    1. Not sure, but there are places to post for trades: GardenWeb and Dave's Garden. I have some natives growing by the creek, but the shade is so heavy there that they don't grow well. I am a bit afraid of transplanting them since they may not be the best edible type and may be invasive. if I am going to deal with an invasive plant, I want it to be a good, useful variety. I'll try it in pots.

  2. Im a permacultural gardener from Norway having a hard time finding any varieties for sale or trade. Please let meknow if you can help me out. I do havea lot of Scandinavian heirloom varieties to trade e.g 4 varieties of Caucasian spinach, the most productive early spring vegetable ever.

    1. Guren, if you are still interested in Apios americana,this site has 3 of the LSU domestication program varieties still in stock:

      They have a couple more that I presume they need to harvest first.