Alpine Knotweed, Alaska wild rhubarb
Polygonum alpinum

Family: Polygonaceae

What it is like

Polygonum alpinum is a PERENNIAL growing to 1 m (3ft 3in) by 1 m (3ft 3in). See above for USDA hardiness. It is hardy to UK zone 5. It is in flower from June to July. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects. 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

Where it is found

Damp meadows, wood margins and mixed grass steppes. Open humus-rich slopes, 2200 - 2700 metres in Kashmir.

Europe to E. Asia.

Conservation Status:

Countries/locations it is found in

How it is used

Food

Rating: 2

Leaves - raw or cooked. They have an acid flavour and can be used as a sorrel substitute. The chopped leaves and stems have been added to a thick pudding of flour and sugar then eaten. Leaf stems - raw or cooked. An acid flavour, they can be cut into sections and used like rhubarb (Rheum spp). The juice from the plant has been sweetened and used as a refreshing drink. Seed - raw or cooked. It is rather small and fiddly to utilize.

Seed: includes nuts, cereals, peas and beans.

Stem: this often intergrades into leaves.

Drink: not including plant saps, tea or coffee substitutes.

Medicine

Rating: 1

The whole plant is astringent. The raw roots and stem bases have been chewed as a treatment for coughs and colds.

Astringent: Produces contraction in living tissue, reducing the flow of secretions and discharges of blood, mucus, diarrhoea etc.

Pectoral: Relieves respiratory diseases, a remedy for chest diseases.

Other

Rating:

How it is grown

Succeeds in an ordinary garden soil but prefers a moisture retentive not too fertile soil in sun or part shade. Grows well near water. Repays generous treatment. Plants seem to be immune to the predations of rabbits. Plants can be invasive but they are easily controlled by spading around the clump.

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: Woodland Garden Dappled Shade; Shady Edge;

Habit: Perennial

Hardiness: 4-8

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

P. undulatum