Because of this extensive root system it can be a strong competitor with other plants and is often difficult to control. Also because of this extensive root system, it is known to many farmers as devil's shoestring. Another perennial in the Polygonaceae family that can be a problem in agronomic crops, especially in no-till situations, is curly dock. This is a taprooted perennial that develops a basal rosette of wavy-margined leaves. Curly dock reproduces by seed, and the young leaves of the seedlings are generally egg shaped.
Perennial plants emerge from the taproot in mid-spring and can be controlled by tillage.
Remember that since it is a member the Polygonaceae family, it will have an ocrea at the base of the leaves. Red sorrel is a rhizomatous perennial that can be a problem in pastures that are not maintained. Red sorrel plants accumulate a high concentration of soluble oxalates, which give them a sour taste and can occasionally cause fatalities in livestock, particularly sheep. The final Polygonum species that we will describe is Japanese knotweed. This species is also a rhizomatous perennial.