What is Knotwood?

Knotwood is a plant native to Eastern Asia which is treated as an invasive species in most other parts of the world, due to its rapid growth habit and the fact that it chokes out native species extremely effectively. The plant is known by a wide range of alternate names, including knotweed, Mexican bamboo, Japanese knotwood, Hancock's curse, Itadori, and Japanese fleece flower. There are a number of uses for knotwood, although this is poor consolation for people who struggle with the plant in their gardens.

As is sometimes the case in taxonomy, there are conflicting scientific names for knotwood. Many people call it Polygonum cuspidatum, but it may also be referred to as Reynoutria japonica, Fallopia japonica, Pleuropterus cuspidatus, or P. sieboldii, among others. As a general rule, P. cuspidatum is the accepted scientific name for knotwood. The alternate names can be used to trace a history of simultaneous discoveries, erroneous classifications, or attempts to name the plant after prominent botanists.

This perennial plant gets quite large if allowed to grow unchecked, and knotwood will also sprawl wildly across the landscape. It has thick, hollow stalks which are broken into segments by swollen joints which superficially resemble knots or flaws in the parent plant. Knotwood has simple leaves, and white flowers which grow on spindly stalks. Knotwood will grow year round, and if cut back, it will resprout from existing roots, making it very difficult to successfully eradicate.

Originally, knotwood was brought to the West as an ornamental. British and American gardeners liked the look of the plant, as it can be coaxed into a pleasing shape and it stays green for most of the year. However, knotwood quickly got out of control, and on any neglected land, it will take over. This is an especially common problem at dumps and composting facilities in areas which are infested by knotwood, since people throw cuttings into the garbage and they sprout.

The roots of knotwood are used in Traditional Chinese Medicine, where they are known as huzhang roots. Knotwood tinctures may also be known as He Shou Wou, and they are used as general tonics for the blood. The plant is also a source of resveratol, a compound used in some nutritional supplements. In addition, the tender young stems of knotwood are edible, and they can be prepared much like rhubarb. Despite these useful applications, many organizations which promote native plants urge gardeners to consider alternatives to knotwood if they are thinking about planting it, since it is so difficult to control.

Knotwood refers to the wood within a tree that forms around a base of a branch or a dormant bud. These dense, irregularly-shaped areas are structurally different from the surrounding wood, often resulting in distinctive patterns that are both visually appealing and challenging for woodworking due to their complex grain.

Knotwood can compromise the strength of timber because knots disrupt the uniformity of the wood's grain, creating weak points. According to the USDA Forest Service, knots are one of the main defects that reduce lumber strength, which is crucial to consider in construction and manufacturing applications where structural integrity is paramount.

Yes, knotwood is often used in furniture making for its unique aesthetic appeal. While it can be more difficult to work with due to its irregular grain, skilled craftsmen value knots for the character they add to wooden pieces. However, the placement and size of knots must be considered to ensure the furniture's durability and functionality.

The cost of knotwood versus regular wood varies depending on the species of tree and the application of the wood. In some cases, wood with a high number of visible knots can be less expensive due to perceived imperfections. Conversely, certain types of knotty woods, like those used for decorative purposes, may command higher prices for their unique appearance.

Knotwood is often sought after for decorative purposes, as the knots can add a rustic or unique character to wood products. It's commonly used in paneling, cabinetry, and furniture where the visual appeal of the knots is desired. Additionally, when knots are small and well-distributed, they can add to the wood's aesthetic without significantly compromising its strength.

Knots in wood are formed when a tree grows around its branches. As the tree increases in diameter, it envelops the base of the branch, creating a knot. If a branch dies and falls off, the tree continues to grow over the area, resulting in a knot. The appearance and size of the knot depend on the growth pattern of the tree and the size of the branch that was enveloped.