London (change)
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22/09/2013 at 19:49

I've been asked several times when I'm going to dispose of this weed but I can't until I know what it is!

It appeared sometime around July, which was when the following photo was taken. It is now over 6 feet and showing no signs of stopping. No flowers, but it is throwing out a new branch at every leaf node and getting terribly large! The stem, or should I say trunk, is some 2 inches across, and it has roots going up the side, where it is leaning over. The stem is speckled with pink-purple dots, similar to a giant hogweed, starting from the base and spreading up as it matures.

Any suggestions eagerly received.


22/09/2013 at 20:00

Can you do a side on view to show the shape of the plant please

22/09/2013 at 21:02

Could it be Indian Balsam? Impatiens glandulifera?

22/09/2013 at 21:06


22/09/2013 at 21:14
22/09/2013 at 21:23

Thanks for the link, Dove. I never knew that the boiled stems were edible OR that they make a yellow dye OR that the sap is a cure for poison ivy.

22/09/2013 at 22:36

It looks like it could be Himalyam Balsum.

23/09/2013 at 08:55


Looks like it may well be Himalyan balsum - if it is it should be producing pink flowers by now. The bumble bees love the flowerer, howevers if it's the only one around in your neighbourhood I would remove it before the seeds set, otherwise there will be twenty plants next year and a thousand in a couple of years. We have it everywhere around here as we have an unmanaged common nearby. This stuff is even out competing the japanese knotweed!

23/09/2013 at 11:18

If your monster plant is a Himalayan Balsam then get rid of it and don't allow it to seed everywhere.  It has now become a nuisance along river banks even though it is very pretty. Such a shame for an attractive plant and it has  an amazing way of shooting out it's seed with a loud popping sound.   

23/09/2013 at 11:42

Thank you all for your help. I think you are right that it is Himalayan Balsam. Only thing that doesn't seem the same is my plant's stems are green with red speckles, rather than having a solid red stem, but I guess this is natural variation.

I'm surprised it hasn't started flowering yet since it is an annual. I will keep it around until it flowers and then chop it down. I may try boiling it too! Enough to feed the family!

Here it is in all its current monstrosity alongside the fennel and sunflowers, and shots of its rooty base and the speckly stem.


23/09/2013 at 16:57

I'm not convinced. I haven't seen it lately but I remember a sort of translucence to the red stem. and some red on the leaf, maybe the mid rib?

these stems have a coarse solidity to them that  doesn't seem right.

and here we are at the end of september, 6' tall and no flowers

23/09/2013 at 18:08

I agree it's concerning that it's not flowered yet if it's to be an annual. Even my most tortured annuals have managed something. I don't like to think I may have to keep it another year or so before I can know what it is though! Next year I shall not let weeds get my interest!

The stem is indeed very solid and bumpy lower down, which I assume is where roots would come out were they nearer the ground.

I thought it came from the bird seed, as this plant is near to a bird table and all around the base of the table there are what appear to be seedlings of it. I hoe them down frequently, but unfortunately this giant fellow got itself under a cloche and was quite large before I found it, so I don't know for sure it's the same, though it seems likely enough.

The leaves look right for the Himalayan balsam, so I shall have a look through other Impatiens and see if there's another giant that might fit the bill. If only it were Impatiens niamniamensis!

23/09/2013 at 18:38

I should think something out of the bird seed is very likely and not likely to be any sort of impatiens.The first pic didn't say HB to me and the later ones even less so.

23/09/2013 at 19:19

I don't remember Indian Balsam being at all prickly, so no.

Bird seed, once again, the culprit, I think.

23/09/2013 at 19:45

I've looked through the ingredients lists on the bird seed packets and all of them are very much not seeds that would grow into this plant. They are all grass type seeds or sunflower seeds.

23/09/2013 at 20:24

what does it feel like Panoply? if you runyour hand over the leaves. Smooth or rough?.


23/09/2013 at 23:08

Could it be Himalayan knotweed, rather than Balsam?  (Persicaria wallichii)  I can't find many pictures of it on the web, but it grows very tall and into large stands, spreading from underground rhizomes and aerial roots which could be the 'rooty stem'. There is a DEFRA fact sheet, but it doesn't tell you what colour the stem is.

24/09/2013 at 06:09

I like your mysterious plant .

not balsam or knotweed ?

so it could be a gift of a dropped seed from a bird poo

( eaten elswhere)    so continue to watch for a flower

It may be a new  plant we will all want , and make you a fortune!!!

24/09/2013 at 19:25

No signs of it spreading underground so I'm comfortable it's not a knotweed.

Glad someone likes it Patty3! I never thought it'd get this big or last so long unidentified. Was sure it'd have flowered by now. Alas.

The leaves are slightly shiny and smooth nutcutlet. No hairs that I can notice on either side.

24/09/2013 at 20:13

I keep coming back to this one Panoply, I don't like to be beaten. 

I haven't got there yet though

1 to 20 of 28 messages