Polygonum buxiforme montanum (Brenckle) R.J.Davis
Polygonum commixtum Greene
Polygonum howellii Greene
Polygonum montanum (Small) Greene
Polygonum tenue commune Engelm.
Polygonum tenue latifolium Engelm.
Polygonum vagans Greene
Common Name: Douglas' Knotweed
Polygonum douglasii is an erect, unbranched or branched, annual plant that can grow around 5 - 80cm tall[
The plant is harvested from the wild for local use as a food.
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[
N. America - Yukon and British Columbia to Quebec, south to California and NW Mexico, New Mexico, Iowa, Michigan and New Hampshire
Dry, often disturbed places, rock outcrops, sandy ground; at elevations from 300 - 3,000 metres[
Species in this genus generally succeed in an ordinary garden soil, whilst preferring a moisture retentive not too fertile soil in sun or part shade[
]. They generally rpays generous treatment[
Most plants in this genus seem to be immune to the predations of rabbits[
Leaves - raw or cooked.
Seed - dried then ground into a powder and mixed with cornmeal or other cereals for making bread etc[
]. The seed is rather small and fiddly to utilize, it is enclosed in a dry papery hull[
Seed - sow spring in situ