‘Billington’ Hopniss (American Groundnut) Tubers

Apios americana

Origin: Eastern North America (via Louisiana & Western Montana)

Improvement status: Breeding population

Tubers per packet:

5 for $12.50 ($2.50 each)

BOTANICAL SAMPLE – NOT GERMINATION TESTED

Life cycle: Perennial

Called hopniss (or hobbenis) by the Lenape people, and also known as American groundnut, potato bean, cinnamon vine, and America-hodoimo (in Japan), this perennial legume sustained Indigenous peoples across eastern North America for untold generations. Grown commercially in parts of Japan and Korea, it has yet to catch on in the land to which it’s native — but with the increasing popularity of native food plants, and especially native perennials, that may be changing. We hope by offering these tubers (along with true seed — found in this catalogue as “South Jersey Hopniss”), we’re contributing to that process.

Hopniss is a vining perennial legume found from just east of the Rocky Mountains to the Atlantic coast, and from Florida well into Canada. It generally favors a wet habitat like the edge of a pond or lake. It can climb up to twenty feet in a season, but dies back to the ground each winter. Its burgundy-colored flowers are beautiful and distinctive (and delicious batter dipped and fried!).

Scientists tell us that there are two forms of hopniss, a diploid form that is capable of producing seeds (which are tan and blocky little beans) and a triploid form that can only flower, but never produces seeds. But it’s not the seeds that most people are after — though they are edible and delicious, if small — it’s the “groundnut,” the tubers that grow along rhizomatous underground stems. With a similar flavor profile to potatoes (though nuttier, sometimes beany, pea-like, or peanuty), they are adaptable to a range of different preparations: steaming, sauteeing, roasting, drying and grinding into flour, candying, fermenting, and on and on. But while they may resemble potatoes, they are also nutritional powerhouses, with three times the protein (16.5%), twice the iron, and ten times the calcium. They also have a balanced amino acid profile and are loaded with isoflavones known to have anti-carcinogenic effects.

The tubers of hopniss plants vary greatly in size and shape, which is part of what has kept this crop from being cultivated beyond a few localized areas in East Asia (to which it was introduced over a century ago). Concerted efforts to domesticate the plant in the United States were initiated in 1985 under the direction of Dr. William J. Blackmon and Dr. Berthal D. Reynolds along with other colleagues at Louisiana State University in Baton Rouge. Wild hopniss tubers might be found three feet from where the vine emerges from the ground, in any direction, with six or more inches between tubers, which are found strung along rhizomatous stems. They also take two years to reach a size worth harvesting. So the LSU program had multiple goals, including to develop varieties with larger tubers, dense tuber set, single-season production, and productivity when grown without a trellis. Between 1985 and 1994, the Blockmon team collected over 200 wild accessions, produced over 2,200 hybrid lines, and after evaluation saved 53 of these for further analysis. Eventually, Dr. Blackmon retired and the hopniss breeding program at LSU ceased to exist, but thankfully much of that work has been saved, and today the largest collection of hopniss is maintained by Iowa State University professor (and longtime friend of EFN!) Dr. Steven Cannon. Our friend Alex Wenger at Field’s Edge Research Farm in Pennsylvania is also doing important breeding work with hopniss.

In addition to offering seeds, we are thrilled to be selling these hopniss tubers this year, produced by EFN grower Michael Billington in Montana. Here’s Michael’s description of what you’ll be getting:

“These groundnuts are from a wide array of improved cultivars and wild collections. Origin genetics are from William Whitson of Cultivariable, Dr. Bill Blackmon of LSU (Blackmon 2127, 2183 and 1972), John Sherck of Indiana, and Norton Naturals. They were then subject to zone 5 conditions with little aid other than sufficient irrigation. This led to a lot of winter-kill initially. Those that were able to form the largest tubers — despite the temperature swings, short season, and day-length challenges of Western Montana — were replanted. Six years later, two distinct selections are becoming prominent. One has long rounded tubers with light tan skin, averaging 2 ½” in length, and with huge amounts of rhizobia attached. The other has darker thicker smoother skin, tubers that are more spherical and grow to the size of a golfball. Both varieties have been selected because of their dense chains of tubers and their size. These varieties both have chains so dense that it’s common to see two adjacent tubers grow so large that they merge into a single lumpy one!”

We’re beyond excited to have both hopniss tubers and seeds in the catalogue for the first time this year — and we’re very much looking forward to seeing what new varieties you all develop from these offerings!

GROWING TIPS: Keep tubers in fridge until ready to plant in the spring. Check them periodically for mold and rinse off as necessary. Choose a site with rich and ideally damp soil. The wettest corner of your garden is the place they’ll be happiest. They can handle some shade, but will be most productive in full sun. The vines can grow quite long, but a 6-8ft trellis should be adequate. Alternatively, they can be grown along a fence or some sort of vegetation that won’t be bothered by them (think rose-of-sharon hibiscus, forsythia, boxwood, etc). If you get the timing right, they can be grown in partnership with taller annual plants like sunflowers, corn, sorghum, or okra.