In response to this guidance, several lenders have relaxed their criteria in relation to discovery of the plant. As recently as 2012, the policy at the Woolwich (part of Barclays plc) was "if Japanese knotweed is found on or near the property then a case will be declined due to the invasive nature of the plant. " Their criteria have since been relaxed to a category-based system depending on whether the plant is discovered on a neighbouring property (categories 1 and 2) or the property itself (categories 3 and 4) incorporating proximity to the property curtilage and the main buildings. Even in a worst-case scenario (category 4), where the plant is "within 7 metres of the main building, habitable spaces, conservatory and/or garage and any permanent outbuilding, either within the curtilage of the property or on neighbouring land; and/or is causing serious damage to permanent outbuildings, associated structures, drains, paths, boundary walls and fences" Woolwich lending criteria now specify that this property may be acceptable if "remedial treatment by a Property Care Association (PCA) registered firm has been satisfactorily completed. Treatment must be covered by a minimum 10-year insurance-backed guarantee, which is property specific and transferable to subsequent owners and any mortgagee in possession. " Santander have relaxed their attitude in a similar fashion.
Fallopia japonica , synonyms Reynoutria japonica and Polygonum cuspidatum , commonly known as Asian knotweed  or Japanese knotweed ,  is a large, herbaceous perennial plant of the knotweed and buckwheat family Polygonaceae . It is native to East Asia in Japan , China and Korea . In North America and Europe , the species has successfully established in numerous habitats and is classified as an invasive species in several countries.