Reynoutria japonica, synonyms Fallopia japonica and Polygonum cuspidatum, is a species of herbaceous perennial plant in the knotweed and buckwheat family Polygonaceae. Common names include Japanese knotweed and Asian knotweed. It is native to East Asia in Japan, China and Korea. In North America and Europe, the species has successfully established itself in numerous habitats, and is classified as a pest and invasive species in several countries. Japanese knotweed has hollow stems with distinct raised nodes that give it the appearance of bamboo, though it is not related. While stems may reach a maximum height of each growing season, it is typical to see much smaller plants in places where they sprout through cracks in the pavement or are repeatedly cut down. The leaves are broad oval with a truncated base, long and broad, with an entire margin. The flowers are small, cream or white, produced in erect racemes long in late summer and early autumn. Related species include giant knotweed (Reynoutria sachalinensis, syns. Fallopia sachalinensis, Polygonum sachalinense) and Russian vine (Fallopia baldschuanica, syn. Polygonum baldschuanicum). Names Common names for Japanese knotweed include fleeceflower, Himalayan fleece vine, billyweed, monkeyweed, monkey fungus, elephant ears, pea shooters, donkey rhubarb, American bamboo, and Mexican bamboo, among many others, depending on country and location. In Japanese, the name is . The kanji expression is from the Chinese meaning 'tiger stick'. One interpretation of the Japanese name is that it comes from 'remove pain' (alluding to its painkilling use), though there are other etymological explanations offered. Identification Identification of Japanese knotweed is not always easy. Many other plants are suspected of being knotweed, due often to the similar appearance of leaves and stems. Dogwood, lilac, houttuynia (Houttuynia cordata), ornamental bistorts such as red bistort (Persicaria amplexicaulis), lesser knotweed (Koenigia campanulata), Himalayan balsam (Impatiens glandulifera), broad-leaved dock (Rumex obtusifolius), bindweed (Convolvulus arvensis), bamboo, Himalayan honeysuckle (Leycesteria formosa), and Russian vine (Fallopia baldschuanica) have been suspected of being Reynoutria japonica. New leaves of Reynoutria japonica are dark red and long; young leaves are green and rolled back with dark red veins; leaves are green and shaped like a heart flattened at the base, or a shield, and are usually around long. Mature R.japonica forms , dense thickets. The stems look somewhat like bamboo, with rings and purple speckles. Leaves shoot from the stem nodes alternately in a zigzag pattern. Mature, healthy stems are hollow and not woody.