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Common Name: Great Water Dock
Rumex hydrolapathum is a perennial plant that can grow up to 1.80 metres tall.
It is harvested from the wild for local use as a food, medicine and source of materials.
Plants can contain quite high levels of oxalic acid, which is what gives the leaves of many members of this genus an acid-lemon flavour. Perfectly alright in small quantities, the leaves should not be eaten in large amounts since the oxalic acid can lock-up other nutrients in the food, especially calcium, thus causing mineral deficiencies. The oxalic acid content will be reduced if the plant is cooked. 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[
Western Europe, including Britain, from Scandanavia south and east to Spain, Italy and S. Russia.
Near ponds and streams, also in shallow water, avoiding acid conditions[
Requires a moist or wet soil, also succeeding in shallow water. Avoids acid conditions in the wild.
A very important food plant for the caterpillars of many species of butterfly[
Young leaves - cooked[
Seed - raw or cooked. It can be ground into a powder and used as a flour[
]. The seed is small and rather fiddly to harvest.
The root is antiscorbutic and strongly astringent[
]. It is harvested in early spring and dried for later use[
The green leaves are said to be an excellent application for ulcers of the eyes[
The roots contain tannin. In cultivated plants, those grown on dry land contained 6 - 8% tannin whilst those grown in water contained 12.4 - 21.6%[
The dried and powdered root makes a good tooth cleaner[
Dark green to brown and dark grey dyes can be obtained from the roots of many species in this genus, They do not need a mordant[
Seed - sow spring in situ.
Division in spring.