Fallopian japonica - Japanese Knotweed

Question 1

Fallopian japonica - Japanese Knotweed

General.

Answer 1

Native to East Asia.
Invasive plant in UK.
Found in the wild over wide areas if UK
Creates serious problems with biodiversity, water and flood control.
Can tolerate wide range of soil types, soil pH and salt concentrations; also frost and water logging.
Rhizomes can destroy concrete foundations, buildings walls etc.

Question 2

Fallopia japonica - Japanese Knotweed.

Appearance

Answer 2

Hollow stems, swollen stem nodes. Canes often have purple flecking
Visual appearance similar to bamboo.
3 - 4m growth in height over one season.
Oval leaves and small cream/white flowers in erect racemes.(summer or early autumn).
Foliage and canes die back in winter as they are frost sensitive, in spring new shoots appear at the base of previous year’s dead canes.

Question 3

Fallopiajaponica - Japanese Knotweed

Root system

Answer 3

Rhizomes tolerate temperatures as low as -35° C.
Can penetrate 7m horizontally and 3m deep.
Rhizomes can spread through water.

Question 4

Fallopian japonica - Japanese Knotweed

Spread

Answer 4

Originally introduced in 19th century as an ornamental plant.
Spread through movement of top soil containing rhizomes .
Species has ability to propagate from small sections of rhizome cut from plant.
Deliberately plant in the wild is illegal in uK