Unlike the other species, the Himalayan knotweed grows close to the ground, aiding in its dense nature. New shoots start to arise during the early spring. Himalayan Knotweed. Reynoutria x bohemica) Bohemian knotweed (Fallopia Bohemica syn. It’s a large, thicket-forming plant, reaching up to 2m tall, and has become established on stream sides, hedge banks, woodland edges, roadsides, railway banks and waste ground. Japanese knotweed, giant hogweed and Himalayan balsam are three of the most common invasive non-native plants in Northern Ireland. These are giant knotweed (Fallopia sachalinensis), Japanese knotweed (F. japonica) and Bohemian knotweed (F. x bohemica). Knotweed Family Identification. Identification: Himalayan knotweed is a perennial, herbaceous plant with a woody root. Control of knotweed is challenging and often requires a watershed approach to be effective along waterways. Japanese knotweed. A non-native invasive plant. Bohemian knotweed Giant knotweed Dwarf knotweed Himalayan knotweed. Himalayan knotweed is highly invasive as it spreads vegetatively, grows quickly, shading out native species, and is a habitat generalist. Polygonum wallichii Himalayan knotweed is very distinct. Appearance. It has a hollow stem, similar to … Himalayan Knotweed Persicaria wallichii This plant is in a different family from the three knotweeds above, and looks more elegant than them. Knotweed is a highly invasive perennial weed which can cause severe damage to both residential and commercial property. Himalayan knotweed flowers are usually pinkish/white. This plant is similar to Japanese knotweed, but has longer, pointed leaves. County-led knotweed control projects. Koenigia polystachya is a species of flowering plant in the knotweed family, known by the common names Himalayan knotweed and cultivated knotweed.It has several regularly used synonyms, including Polygonum polystachyum, Aconogonon polystachyum and Persicaria wallichii.. Koenigia polystachya is native to Asia (southwestern China, Indian Subcontinent, Myanmar, Afghanistan) and it is planted … The flowers range from fuchsia to pale pink in colour and tend to appear between June and October, followed by seed pods … Like other knotweed species, it is difficult and expensive to control. Stems are 2-3 m tall and are branched in the upper half. It forms dense clumps which can be up to three metres in height. The growing patterns, leaf structures, interior stem, and pink flowers set this plant apart. Himalayan knotweed (Persicaria wallichii) The most distinctive of these species, it tends to be shorter, denser and more clump-forming and has pinker flowers and stems that are not hollow. It can cause declines in native plants, including rare or localised species, due to their quick growth and shading out other plants. Himalayan Balsam identification. Himalayan knotweed leaves are narrow (its width is less than half its length), distinguishing it from giant, Japanese and Bohemian knotweeds, which have leaf widths more than 2/3 their length. I only include it because it does sometimes get confused with these other species. They are very fast growers and can reach full height by the end of June. Himalayan Balsam is a distinctive plant with reddish jointed stems and long, green, oval-shaped leaves. The leaf base of giant knotweed is deeply heart shaped compared to the base of Japanese knotweed, which forms a right angle with the leaf stem. 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