Japanese knotweed has many defining traits and characteristics that differentiate it from other plants. From the ground up, the plant is recognizable for its tall, thin, tightly-bunched stems. These structures are usually green with red flecks, though this coloration can differ slightly between plants. They can also be quite tall- prolific plants can have stems that grow to heights of over ten feet. Leaves branch out from these stalks at structures called nodes, which give the plant its bamboo-like appearance. At the top of the stalks, plants have many leaves and small strings of white flowers, which can be seen in the photo to the right.

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The plant's subterranean structures are perhaps more interesting than those above the ground. The plant's stalks often grow out of large clumps of roots, some of which can be visible from above the ground. Roots can descend almost ten feet below the ground, if they are able to. 

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Roots are not the only structures that the plant creates underground, however. It is also capable of growing extensive systems of rhizomes, also known as rootstalks or runners. These are essentially horizontal stems, and they are capable of surfacing and growing vertically over twenty feet away from the original plant. They allow the plant to grow prolifically over large areas of land, and their strong growth is often able to damage manmade structures, especially roads. These structures have played a large role in allowing Japanese knotweed to invade and thrive in environments across the world. A sketch of these structures can be seen to the right.

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