Plant Portrait - Apios Americana American Groundnut

The American ground nut, which although related to peanuts should not be confused with them, is a climbing perennial plant from the woodland edges of N. America. It produces new shoots each year from numerous underground tubers, these new shoots twining around any supports they can find and growing perhaps 1.2 or more metres long.

This is a very easy plant to grow, preferring a light rich soil and a sunny position. When grown in a warm dry situation in a well-drained sandy soil, the plants will be long lived with the tuberous roots increasing in size and number each year. The plant prefers light dappled shade in its native environment, though it seems to need a sunnier position in Britain. Perhaps siting it on the sunny edge of a woodland, or along the sunny side of a garden shrubbery would be most suitable for it. The groundnut is also said to be very tolerant of acid soils though it dislikes windy situations.

The groundnut has occasionally been cultivated for its edible tubers and has the potential to become a commercial crop. Wild plants can produce yields of a kilo or more of tubers so long as they are left to grow for 2 years before harvesting them. Research work in N. America has produced cultivars with yields of 2 kilos or more and it is said that the yields from some of these cultivars can rival potato crops. We have recently obtained some of these forms and hope to release them on trial within the next few years.

The tubers can be eaten either raw or cooked. Although rather starchy and chewy raw, when cooked they have a soft, floury texture and a pleasant mild slightly sweet flavour reminiscent of sweet potatoes - they can be eaten in quantity and make an excellent stodge part of the meal. In taste trials that we have run, this tuber always comes out near the top of the list. The tubers can be dried and ground into a powder then used as a sweetener and thickener in soups or can be added to flour. They contain about 17% crude protein, which is more than 3 times that found in potatoes.

The tubers are very easy to harvest, and you can often collect quite a quantity without even having to dig the soil. This is because they are formed quite near the soil surface, the plant forming long thin roots that enlarge at intervals along their length to form the tubers. To harvest, you scrabble about in the soil until finding a root, you then gently pull upon it and, with luck, you will end up with a long length of root containing a number of swollen tubers, the effect being somewhat like a necklace.

Another benefit of growing this plant is that it has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric

nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby. Thus this is a very good companion plant in woodland and other integrated plantings.

Propagation is quite a simple matter. Division of the tubers can be carried out in the autumn or spring - either replant immediately or store them in a cool but frost-free place until the spring. Make sure you do not let them dry out as the tubers will quickly wither unless kept moist.

Seed is also a simple matter. Pre-soak it for 3 - 12 hours in tepid water, by which time it should have swollen to about twice its size, and then sow February/March in a cold frame. The seed usually germinates in 1 - 3 months at 15°c[134]. When large enough to handle, prick the seedlings out into individual pots and grow them on in light shade in the greenhouse for their first winter, planting them out in late spring or early summer.

The only problem we have ever had with growing this species is that slugs and snails adore the young shoots in spring so, if you are blessed with active populations of these lovely creatures, make sure to give the plants some protection in the spring.

Image Attribution: flickr.com/photos/gmayfield10, flickr.com/photos/53817483@N00