Japanese Knotweed

I decided to create a separate page for the Japanese Knotweed as I'm accumulating a lot of photos of it, having observed 5 occurences of it near me. I like to keep an eye on any Japanese knotweed I see  - how fast it grows, does it get invasive, is it flowering?

End of October 2018, I went over to Regent's Park to check on one I saw last winter, which wasn't flowering at that time but it was flowering today. My first photos of Japanese knotweed flowers and buds.

japanese knotweed flowers

It was only when updating my blog here, I see the photos above and below are so similar. Not sure which is better.

japanese knotweed flowers

japanese knotweed flowers

spray of buds there on the left

japanese knotweed

japanese knotweed buds

japanese knotweed

japanese knotweed

November 10 2018

This is the largest most established example I've seen, near the example above, I only discovered a few days ago so not sure how long it's been in bloom.

japanese knotweed flowers

the flowers spikes are growing straight up

japanese knotweed flowers

japanese knotweed flowers

close-up of some flowers, these are past their prime and I can see the seedhead forming in the centre of the flower, although I've heard knotweed doesn't spread by seed so does it produce seeds?

japanese knotweed flowers

this, like so many plants I see, has reddish tinge and I don't think that's the plant, I think that's the environment, especially as I've seen other reddish plants nearby

japanese knotweed

this is another Japanese knotweed plant but it's smaller and younger and not in bloom

japanese knotweed

another plant nearby

japanese knotweed

May 2018,unlike other small suspected examples I've seen, this Japanese Knotweed is tall. It has a speckled stem with nodes and shield-shaped alternate leaves. 

japanese knotweed

close-up of the stem

japanese knotweed stem close-up

another shoot near the tall plant above, I will go back and measure the leaves

japanese knotweed

Oct 2018 and that Japanese knotweed is in bud.

japanese knotweed buds

japanese knotweed buds

japanese knotweed buds

japanese knotweed buds

japanese knotweed buds

this branch doesn't have any buds

japanese knotweed

November 2017

The first example I noticed as a small shrub along the railings of the London Zoo car park and thought it looked familiar. I don't know why it's a sprawling shrub rather than tall stems.

japanese knotweed

japanese knotweed

japanese knotweed node

I did wonder why such an isolated shrub? so a couple days later I went back and looked further and found 2 more along the railings but still no huge patch of it as you hear horror stories of.

japanese knotweed

this is a wider view of the environment, the first example of the Japanese knotweed is at the base of the lamp post on the far side

the Japanese knotweed is on the right below along the railways, quite far from any gardens across the road

the smallest Japanese knotweed I've seen, small shoot in a front garden round the corner, April 2018

japanese knotweed

that was cut down to the ground but it's back (Nov 2018)! with a few shoots rather than 1 but still reasonably slow-growing

japanese knotweed