Psoralea esculenta

A perennial reaching 1 foot tall, flowering from May to July. Hardy to UK zone 4. Grows in light sandy, medium loamy, and heavy clay soils with good drainage and variable pH tolerance. Prefers full sun and tolerates both dry and moist conditions. Hermaphroditic flowers are insect-pollinated, and the plant fixes nitrogen.

Description

It is a rather stout erect herb. It has some branches and is softly hairy. It keeps growing from year to year. It grows 30-50 cm high and spreads 30-50 cm wide. The roots thicken into potato like tubers or turnips. They are long and have white flesh. These can be 8 cm thick and 15 cm long. The leaves are divided like fingers on a hand and have 5 leaflets. The leaf stalk is usually longer than the blade. The leaflets are fattened oval shape and 2-6 cm long by 0.8-2 cm wide. The flowers are in a dense oblong spike. This can be 10 cm long. The flowers are bluish. The fruit is an oblong hairy pod. It can be 0.5 cm long. It is slightly wrinkled. The seed are brown.

Edible Uses

The root can be eaten raw or cooked, and is best harvested as the tops die down at the end of the growing season. Raw, it has a sweetish, turnip-like taste and is starchy and glutinous. It contains approximately 70% starch, 9% protein, and 5% sugars. The root can also be dried for later use or ground into a powder and combined with cereals to make cakes and porridges. This root was both a staple food and a luxury item for many Native North American tribes.

Traditional Uses

The root contains thick, brown edible starch. They can be dried in the sun and stored. The cake can be ground into flour to make bread or thicken soups. The peeled roots can be eaten raw, boiled, baked, fried or roasted.

Medicinal Uses

An infusion of the dried roots has been used to treat gastro-enteritis, sore throats, and chest problems. Children chewed the roots as a remedy for bowel complaints. A poultice of chewed roots has been applied to sprains and fractures.

Known Hazards

This species contains furanocoumarins, these substances can cause photosensitivity in some people.

Distribution

It is a temperate plant. It grows on poorer soils on plains. It suits hardiness zones 3-7.

Where It Grows

Australia, Canada, North America*, USA,

Cultivation

Succeeds in an ordinary garden soil. Requires a well-drained soil in a sunny position. Plants are very intolerant of root disturbance, they are best planted out into their permanent positions whilst still small. This plant has been recommended for improvement through breeding and selection for its edible root. It was sent to Europe around the year 1800 as a potential food crop but was not well received. This species 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.

Propagation

Pre-soak the seed for 24 hours in warm water, then sow in early to mid spring in a greenhouse. Sow directly into individual pots, or pot up seedlings as soon as possible to avoid root disturbance, growing them on in pots until planting out in their final positions. Transplanting this species almost always causes fatal root damage. Division can be attempted in spring with great care, but the plant strongly resents root disturbance and successful division is virtually impossible.

Other Uses

The plant is a good soil stabilizer in its natural environment and is a nitrogen fixer. An oil is also associated with this plant.

Production

The tubers are collected at the end of the growing season when the tops die down.

Other Information

A significant food.

Notes

The tubers have a protein content of 7%.

Nutrition

Synonyms

Also Known As

Breadroot, Indian turnip, Navet de prairie, Pomme blanche, Pomme de prairie, Prairie parsnip, Prairie potato, Prairie turnip, Timpsula, Tipsin

References (24)

• Beckstrom-Sternberg, Stephen M., and James A. Duke. "The Foodplant Database." http://probe.nalusda.gov:8300/cgi-bin/browse/foodplantdb.(ACEDB version 4.0 - data version July 1994)
• Burkill, I.H., 1966, A Dictionary of the Economic Products of the Malay Peninsula. Ministry of Agriculture and Cooperatives, Kuala Lumpur, Malaysia. Vol 2 (I-Z) p 1851
• Cormack, R. G. H., 1967, Wild Flowers of Alberta. Commercial Printers Edmonton, Canada. p 187
• Cundall, P., (ed.), 2004, Gardening Australia: flora: the gardener's bible. ABC Books. p 994 (As Pediomelum esculentum)
• Elias, T.S. & Dykeman P.A., 1990, Edible Wild Plants. A North American Field guide. Sterling, New York p 150

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