Polygonum conspicuum

Family: Polygonaceae

What it is like

Polygonum conspicuum is a PERENNIAL growing to 0.6 m (2ft). It is in flower from July to October, and the seeds ripen from August to October. The species is dioecious (individual flowers are either male or female, but only one sex is to be found on any one plant so both male and female plants must be grown if seed is required). . The plant is not self-fertile. 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): 0.6

Where it is found

Wet sunny places in lowland, C. and S. Japan. Streamsides and riverbanks from sea level to 1500 metres in eastern China.

E. Asia - China, Japan, Korea.

Conservation Status:

Countries/locations it is found in

How it is used

Food

Rating: 1

Leaves - raw or cooked. Seed - raw or cooked. It is rather small and fiddly to utilize.

Medicine

Rating: 0

Other

Rating:

How it is grown

We have very little information on this species and do not know if it is hardy in Britain, though judging by its native range it should succeed outdoors in most parts of the country. It is very closely related to P. japonicum - this report indicates that it could be a very invasive plant since P. japonicum is the Japanese knotweed. It is probably inadvisable to bring this plant into Britain without strict precautions. The following notes are based on the general needs of the genus. Succeeds in an ordinary garden soil but prefers a moisture retentive not too fertile soil in sun or part shade. Repays generous treatment. Plants seem to be immune to the predations of rabbits. Dioecious, male and female plants must be grown if seed is required.

Propagating it: 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. Division in spring or autumn. Very easy, larger divisions can be planted out direct into their permanent positions. We have found that it is better to pot up the smaller divisions and grow them on in light shade in a cold frame until they are well established before planting them out in late spring or early summer.

Best place to grow: Cultivated Beds;

Habit: Perennial

Hardiness:

Growth:

Soil: Light (sandy), medium, heavy (clay)

Shade: Semi-shade, no shade

Moisture: Moist

Things to keep in mind

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.

Its other names

Local names

Synonyms

Persicaria conspicua. Nakai.