Many weeds are obscure plants that are easy to miss, but yellow dock is a weed that stands out. It is easy to identify, and the reasons for bothering to identify it include that it is:
Despite its medicinal qualities, Rumex crispus is listed as a plant poisonous to dogs by the ASPCA.
Botanical Classification for Yellow Dock Plants
Plant taxonomy classifies yellow dock as Rumex crispus. It is considered a broadleaf, perennial "weed," "wildflower," or "herb," depending on your perspective. This curious plant belongs to the buckwheat family, which is identified by the nodes that punctuate the plants' stems (an even clearer example being those found on Japanese knotweed). It is in the same genus as another weed commonly found in North America, sheep sorrel (Rumex acetosella).
Yellow Dock Plant Identification
The distinct flower head of the plant that remains after the blooms have dried and turned brown is helpful for the identification of yellow dock. The flowers start out a much less distinctive light-greenish color (they can have a reddish tinge, too). Blooming occurs in clusters in the form of multiple, long, skinny flower stalks at the top of the plant.
The plant's dark green leaves will further help you identify it when you find it. The bottom leaves can be quite long, ranging from 1/2 foot to 1 foot in length. Look, in particular, for the sword-like shape and the curled edges of the foliage. It is from this curly leaf margin that the weed gets the nickname of "curly dock." This alternate common name is also sometimes given as "curled dock"; the species name, crispus is Latin for "curly."
Another aid in identifying this weed is its height. The plant reaches as much as 4 feet tall at maturity. A related weed can also grow to be as much as 4 feet tall: bitter, or "broadleaf" dock (Rumex obtusifolius). But it is easy to tell the two apart: True to its name, the broadleaf type has bottom, or "basal" leaves that are very wide (4 inches across, versus 1 inch across for yellow dock plants). Whereas the subject of this article has basal leaves shaped like swords, the basal leaves of its relative are shaped more like shields.
Indigenous to Europe, Rumex crispus has become naturalized across much of the world. It often tolerates poor, disturbed soils and is frequently found along roadsides, although it prefers to grow in rich, loamy soils in full sun and with adequate water. In some states of the U.S., yellow dock is considered an invasive plant.
Rumex crispus produces a long taproot. If you are going to try to dig it out, you must dig deep, so as to remove the whole root; otherwise, as a perennial weed, the plant will re-emerge. Those of you aware of the challenges involved in dandelion control will understand this problem.