Earthnut Pea, Tuberous sweetpea
Lathyrus tuberosus
Family: Fabaceae or Leguminosae
What it is like
Lathyrus tuberosus is a PERENNIAL growing to 1.2 m (4ft). See above for USDA hardiness. It is hardy to UK zone 6 and is not frost tender. It is in flower from June to July, and the seeds ripen in August. The species is hermaphrodite (has both male and female organs) and is pollinated by Bees. It can fix Nitrogen. It is noted for attracting wildlife. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.
Height (m): 1.2
Where it is found
Cornfields and hedgerows, avoiding acid soils.
Europe to W. Asia. Naturalized in Britain in a very few sites in E. England.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 5
Root - cooked or raw. Sweet and starchy, it is delicious when baked with a flavour that is somewhat like a sweet potato. Taste trials consistently place this root very highly, it is certainly one of our favourites. Unfortunately, yields are rather low and so the plant is only worthwhile growing as a taste treat, not as a staple crop.
Root: includes bulbs, corms, tubers, rhizomes etc.
Medicine
Rating: 0
Other
Rating: 3
Nitrogen fixer. Attractive flowers. Attracts wildlife.
Attracts Wildlife: Plants noted for attracting wildlife
Food Forest: Plants for Edible Forest Gardens and Food Forests.
Nitrogen Fixer: Plants that fix nitrogen in the soil
How it is grown
An easily grown plant, succeeding in any moderately good garden soil. It prefers a limestone soil in a warm position, and likes some shade. A climbing plant, scrambling through other plants and supporting itself by tendrils. It tends to be slightly invasive with new stems emerging at some distance from the parent plant. The earthnut pea has occasionally been cultivated for its edible root. Slugs are inordinately fond of this plant and will totally destroy it given a chance. A good bee plant. 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. For polyculture design as well as the above-ground architecture (form - tree, shrub etc. and size shown above) information on the habit and root pattern is also useful and given here if available. A suckering vine sending up suckers some distance main plant. The root pattern is tuberous with swollen potato-like roots .
Propagating it: Pre-soak the seed for 24 hours in warm water and then sow in early spring in a cold frame. When they are large enough to handle, prick the seedlings out into individual pots and plant them out in the summer. If you have sufficient seed, then it can also be sown in situ in mid spring. Division of the tubers when the plant is dormant in spring or autumn.
Best place to grow: Woodland Garden Sunny Edge; Dappled Shade; Hedgerow;
Habit: Perennial
Hardiness: 5-9
Growth:
Soil: Light (sandy), medium, heavy (clay)
Shade: Semi-shade, no shade
Moisture: Moist
Things to keep in mind
Although no records of toxicity have been found for this plant, the seed of some species in this genus contain a toxic amino acid that can cause a severe disease of the nervous system known as 'lathyrism' if they are eaten in large amounts (although small quantities are said to be nutritious). Great caution is advised.