Alpine Knotweed, Alaska wild rhubarb

Polygonum alpinum

Physical Characteristics

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.

Distribution

Europe to E. Asia.

Habitats

Woodland Garden Dappled Shade; Shady Edge;

Edible Uses

Edible Parts: Leaves Seed Stem Edible Uses: Drink Leaves - raw or cooked[2, 145]. They have an acid flavour and can be used as a sorrel substitute[74]. The chopped leaves and stems have been added to a thick pudding of flour and sugar then eaten[257]. Leaf stems - raw or cooked. An acid flavour, they can be cut into sections and used like rhubarb (Rheum spp)[257]. The juice from the plant has been sweetened and used as a refreshing drink[257]. Seed - raw or cooked. It is rather small and fiddly to utilize.

Medicinal Uses

Astringent Pectoral The whole plant is astringent[74]. The raw roots and stem bases have been chewed as a treatment for coughs and colds[257].

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[238].