Groundnut AKA potato bean AKA hopniss is a nitrogen-fixing vine in the legume family that bears edible beans and large edible tubers that have numerous health benefits. The vines grow quickly to 10-20 feet, and the flowers are usually pink, purple, or red-brown, similar to wisteria flowers. Its fruit, resembling a green bean, measures 2-5 inches long. Groundnut’s native range is from Southern Canada to Florida and west to the border of Colorado, and it can be found growing wild in marshes, wet thickets, stream banks and bottomland forests.
 
Plant tubers two to three inches deep in a moist area with at least 2 hours of sun. For best production, include sand for drainage, compost and mulch to control weed competition, and provide something to climb on. In its second year, several one-inch-thick tubers can be harvested from each plant. It’s important to give it some space as it is an enthusiastic spreader.
 
Apios is a larval host plant for the silver-spotted skipper.
 
The tubers can be somewhat nutty, but mostly resemble potato, though the texture can be creamier. The protein content is 3 times higher than potatoes (15-30 mg/g), lacking only 2 amino acids (cysteine and methionine) from being a complete protein. A good source of omega-3 linolenic fatty acids, known for their anti-inflammatory effects. Approximately 1/3 of the fresh weight is carbohydrate, and they’re an excellent source of calcium and iron. Consumption of the tubers has been shown in rat studies to lower blood pressure, cholesterol and triglycerides, and has a history of use by Native Americans for balancing hormones, due to the genistein and isoflavone content. Genistein-7-O-gentiobioside is a novel isoflavone found in the American groundnut that has been shown to have anti-carcinogenic function against colon, prostate, and breast cancer. Raw tubers should not be consumed as they contain protease inhibitors that are denatured by cooking.