Curly dock (Rumex crispus) is a member of the Buckwheat Family, a native of Eurasia now naturalized throughout North America. Narrowleaf dock, sour dock, yellow dock, and curlyleaf dock are a few of the other colloquial names for R. crispus.
A perennial, curly dock can be found in waste lands, wet meadows, along ditch-banks and flood lands. When it invades cultivated crops, curly dock is considered a noxious weed.
Growing between 2 and 5 feet in height, curly dock grows from a thick, fleshy taproot that looks yellowish when cut. (Perhaps this is where the common name, yellow dock, derives.) The erect stems, often reddish and slightly ridged, are generally unbranched below the inflorescence.
The alternate leaves are bluish green, lance-shaped and wavy or curly along the edges. In the fall a rosette of leaves forms at the base of the stem. The remainder of the plant turns dark brown and dies back over the winter.
Green flowers are rare in the plant world. Curly dock flowers are at the top of the stems in long, loosely-branched, spike-like, terminal clusters. The flowers have no petals, instead there are three green inner sepals and three green outer sepals. There are two types of flowers on the plants: female pistillate flowers containing 3 styles and bisexual flowers that have 6 stamens in addition to the styles.
The inner parts of the curly dock flower enlarge to form a papery, heart-shaped structure that surrounds the small, triangular seeds. The seeds (achenes) turn from reddish brown to black as they mature. The seeds are distributed by the wind. Because they are slightly sticky the seeds also adhere to clothing and animal fur, aiding in their dispersal. The inflorescence (and even the entire plant) turns reddish brown at maturity.
Curly dock, because it accumulates oxalates and nitrates, can poison livestock. Young curly dock leaves can be eaten if they are boiled in several changes of water to remove the oxalates. (Why bother?) Occasionally, small amounts of raw leaves can be safely added to a salad. As the plant ages the leaves become bitter and unpalatable.
Herbalists use curly dock root to treat anemia because of high concentrations of iron in the roots. Concoctions made from the leaves treat respiratory ailments. Care must be taken when using this plant because of its high oxalate and nitrate titers.
Because the flowers are wind pollinated bees do not visit curly dock. However, the caterpillars of some butterflies and moths eat the foliage and other plant parts. Birds and small mammals supplement their diets with curly dock seeds.
These curly dock plants were growing near the Crystal Lake Fish Hatchery (Lassen County CA).