How do you identify weeds?

Question

How do you identify weeds, is there some process?

I ask as I have this weed (see image) that constantly returns all over my garden and my efforts to find it online have come to nothing.

Scotland, U.K.

The red weed...uuuulllaaa

Where are you located? A location would likely help in identification. — renesis, Jun 07 '18 at 15:50
It looks to be some sort of [myco-heterotrophic](https://en.wikipedia.org/wiki/Myco-heterotrophy) (non-photosynthesizing) plant... Cool! — renesis, Jun 07 '18 at 16:02
How tall does it get if you leave it, and do the leaves become green, with just red shoots? — Bamboo, Jun 07 '18 at 16:02

Bamboo · Answer 1 · 2018-06-07T16:44:23.403

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I really hope I'm wrong, but I've a horrible suspicion this might be Japanese Knotweed - image here http://treeheritage.co.uk/japanese-knotweed-garden/

If it's everywhere and it is that, I hope its nowhere near your house - it'll punch through into your rooms inside if it is, so if close to the house, I'm afraid you'll need to call in the professionals.

Have you ever left any of it to get taller and grow on? If you have, do you have a photo of it, or can you describe it?

As for identifying weeds, its not that easy on line, what you tend to get shown are images of ordinary flowers and plants which are regularly sold for gardens. Sometimes, if a weed is classed as a wildflower (and they often are) you can find them that way.

edited Jun 07 '18 at 16:44

answered Jun 07 '18 at 16:05

Bamboo

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It’s nowhere near my house. It’s in a raised garden separated from the shed with a thing brick wall then a foot and a half of space. The shed is raised and 20 feed from the house and I’ve never let it grow ... – Ross Drew Jun 07 '18 at 17:50
...it looks a little like the knotweed but knotweed looks much thicker. I’m also in UK, if that means anything. – Ross Drew Jun 07 '18 at 17:52
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@RossDrew yea I know, I checked your profile before answering...might be wise to let one stalk grow to be sure whether its knotweed or not.... – Bamboo Jun 07 '18 at 19:09
In the optimistic hope that it's not knotweed, it could be rosebay willowherb. This sometimes has a red stem and leaves. The leaves of willowherb are unmistakable with those of knotweed so let one grow a foot and see... – David Liam Clayton Jun 08 '18 at 16:51

score 2 · Answer 2 · answered Jun 07 '18 at 16:37

In contribution to your first question, a process for identifying weeds; for USA weeds, I have successfully used the "weed identifier" tool from the University of Wisconsin. You type in all the characteristics you know, and then the weed identifier comes back with photos of all the suspects that meet your "requirements". Browse through until you find it. Even though the weed doesn't have to be from Wisconsin, they only have location choices in the US, but some of these plants are a problem in many different parts of the world, so you might find your culprit there even if your problem is in UK. Also I imagine there are lots of similar websites to be found covering other places.

Good luck with your problem plant. I have to say, it looks deceptively "pretty" in your photo.

Seems to come back with nothing for me, perhaps because I'm in the UK, perhaps because I don't see any way to describe the limited characteristics of something so young. I might actually need to let it grow like others have suggested :( — Ross Drew, Jun 08 '18 at 08:52
Asking the old guy across the street, who has been fighting the stuff for 30 years can be very helpful. — Wayfaring Stranger, Jun 08 '18 at 16:17

How do you identify weeds?

2 Answers2