This species is better known in the literature as Polygonum lapathifolium[].

Common Name: Curlytop Knotweed

General Information

Persicaria lapathifolia is an erect, annual plant growing up to 180cm tall.
The plant is harvested from the wild for local use as a food, medicine and soap.

Known Hazards

Although no specific mention has been made for this species, there have been reports that some members of this genus can cause photosensitivity in susceptible people.
Many species also contain oxalic acid (the distinctive lemony flavour of sorrel) - whilst not toxic this substance can bind up other minerals making them unavailable to the body and leading to mineral deficiency. Having said that, a number of common foods such as sorrel and rhubarb contain oxalic acid and the leaves of most members of this genus are nutritious and beneficial to eat in moderate quantities. Cooking the leaves will reduce their content of oxalic acid. People with a tendency to rheumatism, arthritis, gout, kidney stones or hyperacidity should take especial caution if including this plant in their diet since it can aggravate their condition[].

Botanical References

Range

Temperate regions of the northern hemisphere, including Britain; tropical and subtropical Africa; tropical and subtropical Asia.

Habitat

Swampy thickets, shores, damp clearings and cultivated fields in N. America[]. Marshy ground; at elevations up to 1,500 metres in Nepal[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Annual
Height	0.75 m
Pollinators	Insects
Cultivation Status	Wild

Cultivation Details

The plant can be found from the temperate zone through to the tropics.
Succeeds in an ordinary garden soil[] but prefers a moisture retentive not too fertile soil in sun or part shade[]. Repays generous treatment[].
Stems in contact with damp soil or water may develop adventitious roots from the nodes[].
Plants seem to be immune to the predations of rabbits[].

Edible Uses

Young leaves - raw or cooked[, ]. Eaten as a vegetable[].

We have no specific information for this species, but the seed of most, if not all, members of the genus is edible both raw and cooked, and is potentially a good source of amino acids. Unfortunately the seed is also usually rather small and fiddly to utilize[].

Medicinal

The whole plant is antiseptic and astringent[]. An infusion has been used in the treatment of stomach complaints, VD and fevers[, ].
The plant produces a soft white mass, a froth like that of soap. It is applied externally to burns[].

Other Uses

The plant produces a soft white mass, a froth like that of soap. It is used for bathing and washing clothes[].

Propagation

Seed - sow spring in a cold frame. Germination is usually free and easy. When they are large enough to handle, prick the seedlings out into individual pots and plant them out in the summer if they have reached sufficient size. If not, overwinter them in a cold frame and plant them out the following spring after the last expected frosts.