Fallopian japonica
syn. Reynoutria
“Japanese knotweed” “Ornamental Bamboo”
POLYGONACEAE
Deciduous noxious perennial weed
Zone: hardy to zone 5
Native habitat (range): eastern Asia
Conditions
Soil: any
Moisture: drought tolerant
Light: full sun to deep shade
Exposure: can withstand high heat
Plant size (h x w): fast to 9′ and infinitely spreading
Other: wetlands with high salinity
Aesthetic
Shape/stem: invasively spreading upright mound so strong it will grow through concrete, semi-woody hallow stems with distinct raise nodes, bamboo-like through not related
Leaf: alternate shovel shaped leaves, broad oval, truncated base, entire margin
Flower: dioecious, small, cream/white, produced in erect raceme
Bloom: August, September
Other: spreads like crazy by rhizomes
Treatment (how to…)
NEVER PLANT THIS
Removal: hard to get rid of but possible through persistent mechanical means and by the use of chemicals:
-paint roundup on to the cut stems and repeat until no trace returns
-all removed material must be completely destroyed on site by dying out and then burning
– NEVER take to a municipal dump but to Hartland identified as invasive (see CRD handout)
– there are ongoing experiments in the UK with biological controls
– other option is to remove everything from the bed, wash all roots of its rhizomes on plants you want to keep then replace the soil and re-plant
Propagate: will regrow from any small piece, can grow even through concrete; it could also spread by seed but is dioecious so you rarely if ever see seeds forming
Uses invasive so no use applies, just remove it
Vulnerabilities
Pests and disease: none
Deer resistant: yes
Other animals:
Interest
Local info,: invasive in Victoria, CRD is aggressively killing it when found in our area, phone the invasive species council if you find it and they will take care of it
Nature: noxious invasive thug
Identification (key features): see key features in this photos and refer to overall description above, will see in the toughest conditions or lush in large stands up to 9′ tall that have hallow bamboo-like stalks with distinct nodes
Interesting facts: introduced to North America from Eastern Asia as an ornamental and forage plant in the late 1870’s; defined by the RHS as a thug, by invasive species councils as “controlled waste”; can grow through 2″ of concrete and from a fragment no bigger than a fingernail accounting to the ministry of forest
Cultivars: Fallopian japonica var. compacta – has been found to be less invasive but should be extremely cautious and avoid planting – it is very pretty with heart shaped leaves and pink flowers
shrub or tree; given ideal conditions it will run through other more sensitive plants
displace native species, hazard to wetlands
or less. It is best to get rid of this weed when it is young; as soon as you see a seedling, dig it up and dispose of it. If it is too late for this, it is much harder to remove. Dig up as much of the whole plant and as much of its roots and dispose. Be sure to wear gloves as the plants stems and leaves are painfully prickly. The roots do not tend to live that long (2-3 years) in the soil but the seeds can travel far in the wind making removal difficult to control. Repetitive treatment will be needed. Always remove before it goes to seed.
May need to do this for more than one year. Strong rhizomatous root system. Through it doesn’t produce as much seed, it spreads itself around and will root from any piece of rhizome left behind. .
. west coast island blooms . 
