Landscape & Urban Design Issue 19 2016 | Page 58

Knotweed Knowhow: How To Identify And Distinguish Between Different Types Of Knotweed Japanese knotweed is an impressive species that grows rapidly to a height of 2 – 3 metres (6-10 feet) in a single season. I n the spring, new growth emerges as rapidly growing soft red/purple shoots reminiscent of asparagus spears. The stems are hollow and bamboo-like and can grow as much as 2 cm per day. As the shoots grow into canes the leaves unfurl and the plant turns green, with stem diameters of up to 40 mm (1.6 inches). The stem growth is distinctive with one stem or leaf stem (petiole) per node producing a zigzag pattern in the stem. The extensive rhizome system allows Japanese Knotweed • • Japanese Knotweed Ltd has been trusted with the responsibility of resolving the knotweed problems for thousands of customers. We are the preferred knotweed specialist for possessing an unrivalled Fallopia Japonica The most common type of knotweed • • Smooth mid-green colour leaves • Small creamy white flowers in loose clusters in late summer • Bohemica • • Leaves longer than wide, pointed at the tip with veins reddish purple when immature • Creamy-white flowers appear in dense clusters in late summer/early autumn • Darker green than the japonica Fallopia japonica var. Compacta It reaches only 1-1.8m (40 inches) in height Leaves have crinkled edges and a leathery texture Leaves are variable in shape, up to 11cm/4 inches long and up to 10cm/3.5 inches wide, often curve in concave form Giant Knotweed • Hybrid between Japanese and Giant knotweeds Leaves are larger than Fallopia Japonica, up to 25cm/10 inches long and 18cm/7 inches wide, and in heart shape Our locally based Surveyors, Supervisors and Field Technicians provide a rapid local and friendly service throughout England, Scotland and Wales. Japanese Knotweed Ltd provides a FREE service to identify plants you suspect as being Japanese knotweed (or other invasive plants). Simply email us a picture of the plant and we endeavour to identify it for you, [email protected] White or pale pink flowers appear in late summer, which often mature to dark pink or red Fallopia x bohemica • depth of knowledge and commercial experience to help companies, councils and homeowners alike. Dwarf Japanese Knotweed One stem per node, with a Zig-Zag stem growth pattern • • new shoots to be produced from any part of the rooting system in the spring, with a 1m² stand of knotweed capable of producing as many as 238 new shoots. This new growth forms dense thickets (which are known as ‘stands’) with new shoots remaining interlinked back to the parent plant. • • Fallopia sachalinensis Similar to Fallopia japonica but grows much taller (up to 4-5 metres or 13-14 feet) Much larger elongated leaves, up to 40cm/16 inches long and up to 27cm/11 inches wide Leaves are pointed at the tip, somewhat crinkly & long white hairs on the underside • Creamy-white flowers appear in late summer/early autumn in dense panicles