Rumex hymenosepalus aka Ganagra

Rumex hymenosepalus is a perennial in the Polygonaceae family. Common names include canaigre, tanner's dock and wild rhubarb. Its native range spans west-central North America into northern Mexico. It grows in temperate regions and spreads through rhizomes. In California, it grows in dry, sandy places. These sites lie below about 4,920 feet [1,500 metres]. Plants reach about 3.3 feet [1 metre] tall.

Flowers appear from May to July. Each flower has both male and female organs. Wind carries the pollen between flowers. Gardeners can grow this species in cultivated beds. It accepts sun or light shade. Sow seed where plants will grow in spring. Spring is also the season to divide established plants.

This dock grows in sand, loam and clay. It accepts mildly acid, neutral and mildly alkaline soils. Deep, fertile soil rich in humus suits it best. The soil should hold moisture yet let excess water drain. Published growing guidance favours moist soil. Its dry native sites also suggest some tolerance of dry ground. Plants have been grown for the tannin in their roots. Dried roots contain about 35–60 percent tannin. Older roots contain more than young ones. Wild roots also contain more than cultivated roots. Roots yield yellow, green, brown and grey dyes. These dyes need no mordant to help fix their colour.

Young leaves have a history of use as cooked greens. Changing the cooking water helps remove their bitter tannins. Cooked leaf stalks have a crisp texture and tart taste. They have been used in pies and cooked with sugar. Stems gathered before flowering have also supplied a boiled drink. Seeds can be eaten raw or cooked. Ground seeds can make a thick porridge or baked cakes. These food uses need care because the plant contains oxalic acid. Large servings can reduce the body's access to calcium. Cooking lowers the oxalic acid content. People prone to kidney stones or gout need extra caution. The same warning applies to arthritis, rheumatism and excess stomach acid.

Traditional medicine has used both roots and leafy stems. Washes made from stems and leaves were used on sores and bites. Root preparations were used for diarrhoea, coughs and sore throats. Powdered roots also served as dressings for burns and sores. These records describe past uses, not proof of safe treatment.