The Apios americana, also known as American Groundnut, is a beautiful, fast-growing climbing vine that produces edible tubers. This vine can grow up to 3 m in a season and bears unusual clusters of sweet-scented, burgundy-colored flowers.
I. Appearance and Characteristics
Apios americana, sometimes called the American groundnut, potato bean, hopniss, Indian potato, hodoimo, America-hodoimo, cinnamon vine, or groundnut (not to be confused with other plants in the subfamily Faboideae sometimes known by that name) is a perennial vine that bears edible beans and large edible tubers.
The plant’s natural range is from southern Canada (including Ontario, Quebec, and New Brunswick) down through Florida and west as far as the border of Colorado.
The vine of American groundnuts can grow to 1–6 meters (3+1⁄2–19+1⁄2 feet) long. It has pinnate leaves 8–15 centimeters (3–6 inches) long with 5–7 leaflets. The flowers are usually pink, purple, or red-brown, and are produced in dense racemes 7.5–13 cm (3–5 in) in length. The fruit is a legume (pod) 5–13 cm (2–5 in) long. In botanical terms, the tubers are rhizomatous stems, not roots.
Studies in rats suggest that raw tubers should not be consumed. They contain harmful protease inhibitors that are denatured by cooking.
II. How to Grow and Care
Sunlight and Temperature
In its native range, the potato bean loves the sunlight. Full sun conditions are ideal in zones 3-7, and it’ll be perfectly happy there.
In areas which are outside its normal growing zones, it can still appear. But in these locations, partial shade is best during the hotter times of day. Areas like Texas, where it occasionally grows, are a good example of this.
Temperature-wise, it can tolerate up to subtropical heat levels during the summer months. In the winter, tubers buried in the ground under mulch will survive even in snowy areas. The tubers can also be harvested in fall and stored over the winter, then planted out in early spring again.
Watering and Humidity
Moist to wet soil is preferable for American groundnut. It requires lots of water to keep those huge vines green. Since the Apios americana Medikus tuber vines provide the energy that’s used to form tubers, they’re essential!
In many wild locations, the groundnut develops in woodlands or along waterways. These locations provide ample soil moisture and collect leaf debris as natural mulch.
Gardeners should water whenever the soil begins to dry out. Be sure excess water drains off readily, so it doesn’t pool. But keep it damp enough that your plants aren’t lacking moisture.
Soil
Sandy loam is perfect for this plant. It’s loose enough to allow easy tuber and root penetration, but allows for drainage. The loam retains just enough water to keep the plants happy.
For these, mulching is a necessity. Since they don’t like to dry out at all, be sure there’s plenty of organic material in and on your soil. This will prevent soil moisture evaporation.
While container growing is an option, choose a fairly large one to allow for tuber growth. Stick with one plant per container, and add extra compost. Ensure you water these consistently, as the soil is more prone to drying out in containers.
It prefers acidic to neutral soil. Aim for pH ranges between 5.1 and 7.0.
Fertilizing
Indian potato plants are nitrogen fixers. Like soybeans, they replenish the nitrogen supply in the soil around them. They can maintain at this level for a long time without the need of fertilizers.
Some studies are showing that for tuber cultivation, fertilizer may still be useful for American groundnut. The extra plant food helps plants to develop larger tubers, making them more valuable as a crop.
So, while you don’t have to fertilize American groundnut, you can if you’d like. Small amounts of fertilizer during the plant’s active growing phase can help.
Pruning
While not an invasive plant, the vines of the Indian potato sure can grow like one! This is especially true if you have more than one plant in a given area. You can prune back the tips of the vines of these edible plants to reduce their height.
It can be beneficial to train your American groundnut plant to a trellis. This will make it more manageable and easier to keep from spreading out wide. Weave vines through a larger trellis, or use tomato ties to secure the vines in place.
Propagation
The easiest way to propagate groundnut plants is through division. It doesn’t need to be an entire string of tubers separated from the mass. A single tuber will suffice, or you can use multiple still connected together. Use sterilized pruning shears or a sterile, sharpened shovel blade to cut them apart.
When separating tubers, make note of which end of each tuber was farthest away from the parent plant. I like to use a rubber band to mark that end of the tuber or tuber string segment. When replanting in spring, that end will be where the plant’s shoots and the rhizome-like string of tubers forms.
Tubers can be harvested in fall and stored until spring. Place slightly-damp soil into a plastic bag. Bury the tuber in the soil. Make sure there’s a couple holes poked in the bag above the soil to allow air to reach the tuber. Store in the refrigerator until the ground thaws, then replant.
Apios americana seeds are available, but they’re not reliable. They should be scarified (rubbed with sandpaper to scratch the hard surface) and soaked for at least 3 hours before planting. It can take a while for them to germinate, if they ever do. Germination rates are low for these seeds.
It’s possible to take cuttings of the healthy main vine and use that to start a new plant. Dip the cut end into water and then a rooting hormone powder. Place into lightly-damp potting mix and keep the humidity up around the cutting. Place it in a location that doesn’t get direct sunlight, and check for roots in a month or two. Be sure it always has damp but not soggy soil for best results.
Pests and Diseases
- Common Pests
Surprisingly, only some forms of nematodes are likely to attack Indian potato plants. It tends to be mostly pest-resistant. Add beneficial nematodes to the soil to defeat the baddies!
It does attract deer, but they don’t tend to eat much of these when other plants are around.
Gophers and mice may become problematic for American groundnut. They will dig for the rhizomatic strings of tubers. If you start to see your plants suffering yellowing or dieback, look for evidence of digging nearby.
As a perk, what the American groundnut plant really attracts is beneficial insects. Lacewings are particularly fond of hopniss plants. Planting some of this may help you with the rest of your garden, as long as you keep its growth contained!
- Common Diseases
Currently, no diseases are known to affect American groundnut. This is likely because it mostly grows wild in the United States. There haven’t been significant disease issues in cultivation.
III. Uses and Benefits
The tubers and seeds can both be cooked and eaten.
- By Indigenous peoples of the Americas
The tubers have traditionally been a staple food among most Indigenous peoples of the Americas within the natural range of the plant. In 1749, the travelling Swedish botanist Peter Kalm writes, “Hopniss or Hapniss was the Indian name of a wild plant, which they ate at that time… The roots resemble potatoes, and were boiled by the Indians who ate them instead of bread.” Strachey in 1612 recorded observations of the Indigenous peoples in Virginia: “In June, July, and August they feed upon roots of tockohow, berries, groundnutts, fish, and greene wheate…”
In Eastern Canada, the Jesuit missionary, Le Jeune, observed that the Indigenous peoples there would, “eat, besides, roots, such as the bulbs of the red lily; … another that our French people call ‘Rosary’ because it is distinguished by tubers in the form of beads.” The early author Rafinesque observed that the Cree were cultivating the plant for both its tubers and seeds. The author Brinton wrote in 1885 in regards to the Lenape people, “Of wild fruits and plants they consumed the esculent and nutritious tubers on the roots of the Wild Bean, Apios tuberosa… which the Indians called hobbenis…”
In 1910, Parker writes that the Iroquois were consuming significant quantities of groundnuts up until about thirty years before his writing. The Paris Documents of 1666 record that the sixth tribe of the second division of the Iroquois were identified as, “that of the Potatoe, which they call Schoneschironon” and an illustration of tubers is found in the Paris Documents with the explanation, “This is the manner they paint the tribe of the Potatoe.” The author Gilmore records the use of groundnuts by the Caddoan and Siouan tribes of the Missouri river region, and the authors Prescott and Palmer record its use among the Sioux.
The Indigenous peoples would prepare the tubers in many different ways, such as frying them in animal fat or drying them into flour. Many tribes peel them and dry them in the sun, such as the Menomini who have traditionally built scaffolds of cedar bark covered with mats to dry their tubers for winter use.
The Menomini are recorded as having dried the tubers in maple syrup or making a preserve of Groundnut tubers by boiling them in maple syrup. The Potawatomi have traditionally boiled their tubers. The traditional Meskwaki and Chippewa preparation involves peeling, parboiling, slicing, and drying the tubers. The Chippewa have historically used them as a sort of seasoning in all their foods.
- By Europeans
The Europeans learned to use the American groundnut from the Indigenous peoples of the Americas. As a result, the American groundnut became interwoven with the history of the American colonies and Europe. The early traveler John Brereton was sustained by the “good meat” and “medicinal” qualities of American groundnut during his travels in New England in 1602. In 1613, the followers of Biencourt at Port-Royal ate the tubers to help them survive in the New World. The American groundnut was an important factor in the survival of the Pilgrims during the first few winters of their settlement.
In 1623 the Pilgrims, “having but a small quantity of corn left,” were “forced to live on groundnuts… and such other things that the country afforded… and were easily gotten…” The Pilgrims were taught to find and prepare American groundnut by the Wampanoag people. The groundnut was likely eaten at the harvest festival of November 1621 that is regarded as the first Thanksgiving, although only venison was specifically named as a food item at this meal by a Pilgrim eyewitness account.
Philosopher Henry David Thoreau commented on the nutty flavor and dry texture in October 1852.
It is believed that American groundnuts may have been shipped to Europe as early as 1597. It was listed in 1885 as a European garden crop. In 1845 it was evaluated as a possible alternative potato crop in Ireland during the Great Famine. These early introductions to Europe appear to have resulted in little or no assimilation of the new food into the European diet. A primary reason for this lack of assimilation was that the two-year cycle for an acceptable tuber yield did not match the cropping systems that were familiar to Europeans.
