Contemplating Hopniss, the American Groundnut

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Apios americana, hopniss
Photo by Hank Shaw

When I look at a big bowl of freshly dug American groundnuts, I think of what might have been, and what may yet be.

American groundnut, also called hopniss, if you’ve never heard of it, is the North American answer to the South American potato. It is a tuber from a bean plant, and yes, you can eat the beans and flowers and shoots too, just the way you can with regular beans. But the tuber holds the most potential as a serious food crop.

The first European reference I can find to hopniss is from Sir Walter Raleigh’s 1585 voyage to Virginia. His resident scientist, Thomas Harriot, wrote a report following the voyage about all the potentially useful things he encountered in the New World, including:

Openauk, a kind of root of round form, some of the bigness of walnuts, some far greater, which are found in moist & marish grounds growing many together one by another in ropes, or as though they were fastened with a string. Being boiled or sodden they are very good meat…

Openauk is only one of many names this plant possesses. Apios americana is what we’re now calling it in starchy Latin binomials, but American groundnut — ironic, considering that the actual groundnut, which we call peanuts, is also of American origin — is also called vine potato, ground bean, and a host of lesser monikers. My friend and colleague Sam Thayer likes the hopniss name, and so do I. It’s clear, short and pretty.

Native to North America east of the Great Plains (although it can be found in a few spots as far west as Colorado), American groundnut likes to be in wet places: streambanks, lowland forest edges, pond edges, etc. That said, the plants are drought tolerant as well; a nice trait to possess in this uncertain climate we’ve been experiencing lately. Hopniss will also grow in gardens, as I have been doing since 2011.

The reason it’s taken me so long to write about Apios americana is the primary reason you can’t buy American groundnut in your supermarket: The tubers, to be of any decent size, need two years to mature. That is simply too long if you are growing for the market. Hopniss tubers also grow like a string of peanuts along the root system of the plant, and can be found yards away from where the plant is growing. Another problem if you plan on growing them en masse.

apios americana on roots
Photo by Hank Shaw

Sam, like most Eastern foragers, prefers to forage for hopniss rather than grow it for precisely this reason. He can harvest a bushel bag in a couple hours from the wild, needing only a shovel and the knowledge of a good spot. Hopniss are easy to spot when they are growing. They basically look like any bean you might encounter in a garden, and they smell beany.

As they are perennials, you can spot older plants by looking at the leaf stems: Older plants have more leaflets on that stem then younger ones. If you can trace a vine back to the soil, the vine will be thicker at the soil line in older plants, too. Late in summer and in early autumn, hopniss sports gorgeous, edible flowers.

Photo courtesy of Wikimedia Commons
Photo courtesy of Wikimedia Commons

Those flowers become beans, which are edible if you cook them. Like most beans, both the beans and American groundnut tubers contain protease inhibitors, a sort of “anti-nutrient” that steals nutrition from you if you eat them raw. So cook them, OK?

It’s the tubers you want, though. And here’s the first advantage of hopniss: You can harvest them pretty much whenever the ground is not frozen, although most sources say they are sweetest in late fall and early spring. February is a perfect harvest time for them here in California.

Various sizes of groundnut tubers.
Photo by Hank Shaw

A typical hopniss tuber is, as Harriot mentioned 425 years ago, about the size of a walnut. That, mind you, is a two-year-old tuber. They get bigger, though, and Sam Thayer has found a few larger than the largest potato. Who knows how old that one was! In my garden, I keep tubers larger than an almond and return the smaller ones to the ground, where they will regrow.

How to eat them? Look first to the Indians. Virtually every native group living where hopniss lives used the plant in some way, shape or form. The Cherokee liked the beans. The Menominee cooked the tubers with maple syrup. The Dakota used them like potatoes.

Some sources say to peel the tubers, but I find this is only necessary with really big, old tubers — you can eat those skins, too, but they’ll make you farty. I also tend to peel the tubers because I like their pretty ivory color.

What are they like? At first taste, they are remarkably close to floury potatoes like Russets. The tuber is a little drier than a potato, quite a bit sweeter — but nothing like a sweet potato — and has a definite beany quality. It really is a bean-potato.

Hopniss is denser than a potato so it will require a bit longer to cook. I find that typical tubers take about 30 minutes to get to the “easily mashed” point. They do not reheat well, however. Reheated hopniss gets gluey and gummy. You can (and I have) however eat leftover mashed hopniss at room temperature and it’s fine.

Fried groundnut chips on a plate.
Photo by Holly A. Heyser

American groundnut also fries wonderfully, making some of the finest potato chips or crisps you’ll ever eat. Because they are drier than potatoes, they cook fast and crisp easily. Cut them a little thicker than you would a potato so they don’t dry all the way through. And make sure to salt them the second they come out of the oil or the salt won’t stick.

You can also dry the tubers to make a sort of flour. Both the Mohegans and the Delaware Indians preserved hopniss; hopniss, incidentally, is the Lenape world for the plant. I didn’t peel my tubers when I made flour, so it took on a warm gray hue.

To make the flour I sliced the tubers into discs and dehydrated them completely. Then I put them into my Vitamix blender and kicked the spurs to it. Instant flour. If your blender is not so muscular, you might need to grind it in some other way.

apios americana flour
Photo by Hank Shaw

You can use this flour in any number of ways. The Delaware Indians used it to thicken soups and stews, and it works like a charm. Hopniss flour absorbs a huge amount of water by weight — far more than wheat flour. In this respect it’s a lot like potato flour (which is not the same thing as potato starch, so be careful when you look up recipes).

But if you think about it, hopniss flour is every bit as much a bean flour as it is a “potato” flour. So use it where you might use chickpea flour, such as in an Italian farinata. This is a hopniss farinata with a hopniss skordalia to serve next to it.

groundnut farinata and hopniss skordalia
Photo by Hank Shaw

Skordalia is a Greek dip made from potatoes and garlic, oil and vinegar. It’s basically really loose garlic mashed potatoes with some vinegar. (Recipe follows) Done with hopniss, it’s spectacular. The farinata are good — they taste like the crust on wheat bread — but they need the skordalia to be a real treat.

For now, the only way you will get your hands on hopniss is to forage or grow them yourself. And if you grow them, it will be a long, often frustrating endeavor. But it may not be like that for long.

For a brief, shining time, scientists at Louisiana State University worked to improve yields and tuber set on Apios americana. It worked, and they got up to 7 pounds of tubers per plant in one season. But sadly, that research ended and has only recently been picked up by the plant geeks at Iowa State University. Slowly, improved hopniss tubers are becoming available.

My great hope is to see hopniss become more widespread. It is more than just a potato substitute. It is a world-class food plant that happens to be native to the United States. And that’s a good thing.

Mashed groundnut tubers, made into Greek Skordalia.
Photo by Hank Shaw

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About Hank Shaw

Hey there. Welcome to Hunter Angler Gardener Cook, the internet’s largest source of recipes and know-how for wild foods. I am a chef, author, and yes, hunter, angler, gardener, forager and cook. Follow me on Instagram and on Facebook.

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46 Comments

  1. I loved the article, it was very informative. I want so much to taste this wild potato, apios americana. How can I get some? My friend John told me of this plant and wants to purchase some tubers, but it is hard to find a place to buy from. Please, anyone out there in the foraging world, I want to try this groundnut so do John, can you help us in finding the tuber?
    I can taste it right now, I ate wild jerusalem artichoke which was delicious and hard to come by. John wants to plant the tubers this year if we can get some. Thank you Lucy Meade

  2. My people the Mi’kmaq call this root Sipekne’ which basically means ground nuts, we have used this as a food source for thousands of years, there is archaeological evidence we were making bread by grounding Sipekne’ into flour 3000 years ago. Lescarbot and Braird both describe my people using the root as a food source in their writings dating back as early as 1616. These writings can be found by googling Jesuit Relations.

  3. I brought around a dozen tubers from a guy I found online last year and planted them in a permaculture patch I was starting. I have 50 or so vines coming up this year. I just harvested a few today for dinner tonight and was looking for recipes when I found this page. Very informative. Sounds like I need to let them go for another year or so.

  4. I planted some of these last year, and didn’t even attempt to harvest them because they seemed to be stuggling a bit. Right now, second year, they are flourishing and flowering. Thanks for the great article! I’m really looking forward to pulling some up this fall!

  5. Any advice on transplanting from the wild? I have found them growing around a local lake and want to see how they will do on the banks of a pond nearby. Another question, I was thinking of using the tubers pureed with salted fish for a brandade. Seemed like an obvious one to me Thoughts?

    BTW, I have been making my way through some of your wonderful game recipes. Next up, bear pelmeni.
    Thanks!

  6. I did find this online (but would love to know more about how they spread so I don’t get too close to my veggie garden) Planting Groundnuts: “Groundnuts are easy to plant. They like full to partial sun, adequate moisture, and rich soil amended with organic material. The flowers are about ½ inch in diameter and are red-brown to pink. The vine is hardy in zones 4-9. The tubers spread, so amend a broad area of your soil with compost. Groundnuts are nitrogen-fixers, so they don’t need much fertilizer. Plant your tubers about 3 inches deep next to a lamp post, tree, pergola, or trellis. They’ll grow 6-12 feet, so they’re easier to maintain than other vines. Just be sure not to let your new vine dry out. Here’s the only catch: you have to wait a season or two for the plants to mature before you harvest your crop. By waiting, though, you’ll never have to re-plant, since you’ll never be able to harvest all of the tubers.”

  7. Thanks so much for these recipes.

    I bought 4-5 plants about 6 years ago from Louisiana State University and started growing them in the Hudson valley, in upstate New York (zone 5A). They have subsequently behaved like the native that they are, and are now growing all over my veggie garden as well as escaping out into the surrounding meadow.

    I left them alone for a few years, using only the flowers in summer salads and to decorate cakes. These days however I am finding tubers the size of eggs – which is where your recipes come in!

    I would say my experience growing this plant has been 100% effortless. They are excellent climbers, can compete with grass and other weeds and co-exist very well with cultivated species like peas and beans.

    Great plant to stick in the ground and come back to in a few years!

  8. Although Hopniss sounds mighty nutritious, I quite despise it… It spreads to my vegetable patch from a neighbouring property, choking out the vegetables I grow. I find it spreads all too readily and I’ve found it very difficult to eradicate. Should anyone have tips on how I can rid myself of this invasive tuber forever, I would be so glad for it!

  9. Wow, Curious plant, & I was beginning to get excited about finding this! Alas,… Now I have more research to do though…

    I noted in an article by Sam Thayer that it’s in the legume family… I’m DEATHLY allergic to Peanuts.. Peas, White beans & Lima Beans have gotten me into serious trouble in the past too (not really a Big loss to me as I Can’t Stand the taste of P & LB’s anyway; I just have to take it easy with not eating too many refried beans on my nachos 😉 ) Now the other biggie legume, soy, I’ve slowly grown to be mostly fine with, prolly because our market goods are SATURATED with the stuff! 😉

    At any rate,… after reading that comment about the Severe allergic reaction someone had, I’m thinking I should just stay CLEAR of this puppy, if only for the POTENTIAL risk d/t my familiarity with peanuts. Not likely to find it here in Colorado anyway, but as my son is a Boy Scout & they travel all around the country with various activities, think it’d be cool for him to be able to recognize it whilst out-n-about… Then he can give it a taste n tell me allllll about it. 😉

    THANK YOU for the Very informative post.
    ~Cheers!~
    JO

  10. I’ve seen roots like these at the edge of local waterways but never the flower. Are there other plants with that style of root that might be mistaken for it?

  11. In the southeast, it is very common along sandy openings near streams, especially near bridges. I think Price’s potato-bean (Apios priceana) produces a much, much larger tuber than A. americana…but it’s a Federal T&E species!

  12. Matt: Good points both! I’d read about that allergy thing, but I had seen or heard no evidence of it beyond Sam’s account. Interesting to hear more accounts of it.

    1. “Allergy” doesn’t really seem to be the right word for it. It does seem similar to normal allergies in that people can eat them for a long time, then become sensitized, and then not be able to eat them at all, but the symptoms (like vomiting) aren’t normal allergic symptoms. It seems more like food poisoning or some kind of toxicity issue that most people have some resistance to, at least initially.

  13. I’m almost ashamed to post this. I’d never heard of Hopniss. All throughout the article the one thought that went through my head was “Do you think Katniss ate hopniss?”. I literally couldn’t get it out of my head. I’ll probably dream about Katniss Everdeen tonight 🙂

  14. Hank- Nice piece on hopniss; they certainly are a great food. I wanted to add 2 things. First, for those interested in foraging them, by far the easiest method to gather quantities is to scour eroded stream banks on foot or by canoe following spring high waters. They are frequently eroded out of the bank and dangle, waiting in abundance, to simply be picked up, particularly along stretches of river with somewhat open (ie. not heavily forested) floodplains, at least that’s the case here in VT. And they keep extraordinarily well in the fridge for many months of enjoyment.

    Second, I think it’s worth pointing out that some people can develop significant and progressively worse allergic reactions to this food (stomach upset and severe vomiting, at least). Unfortunately, this has been the case for my partner. Sam Thayer discusses this in his book, Forager’s Harvest, and after conferring with him following the reaction (2012), he suggested lengthy cooking times, perhaps as much as 3 hours, may be important to prevent development of such reactions in some people. Unfortunately the data points are few. It would be great to hear if there’s any new thinking on this point – or if anyone has found a way around the allergy for those already sensitized.

    Thanks for all the fun, informative, and delicious ideas!