Is this a weed?

If you pull a bit up does it have white fleshy roots?

It looks like Rosebay willow herb which is definitely classed as a weed in my garden. The white variety is tolerable though.

The thing that makes me wonder if it is something else is the fact that it is not growing upright but is sort of trailing about.

I'll go and pick a bit up and look at the roots.

Back in a mo!

The small clumps have white thready roots; but the larger clumps have a thicker white more fleshy root.

It's rosebay. There are a number of variants but it's a weed, whatever variety you've got. And it seeds prolifically...

Ah - so I will attack it with my trusty trowel!

Insects like it.

Including bees.

I love Rosebay Willowherb! But not in my garden

It's a wild flower.

There's some in my garden but it has never flowered because roe deer eat it.

Might it be detrimental to the roses in any way?

I find it quite easy to dig out.

Not detrimental as such OP, but weeds take the nitrogen out of the soil and that's not good for any of your cultivated plants. Plus, any feed that you put on your roses will also feed the weeds and you'll get more of them! Rosebay Willow Herb are fairly shallow rooted and so pull out easily enough, you just have to keep on top of them.

It will compete with the roses for moisture and nutrients so I'd get rid of it.

I now have a job for tomorrow! Thanks for all advice.

I agree rosebay willow herb.

Luckygirl It looks very much like the weeds I have been pulling up over the last couple of days. The way the leaves spread out in different directions.
If it is what it seems it is not too deeply rooted as some weeds.

Bin it ASAP.

I once sowed some Astrantia seeds in a tray, following Carol Klein's instructions and nurtured them over winter. The only resulting plant eventually revealed itself to be a Willow Herb! They often pop up in my garden, but as has been said they are easy to pull out.

Might be short fruited willow herb rather than rose bay. I get a lot of it in my garden.

If you think something is a weed, then it usually is, and weeds are generally easier to pull out than ‘plants’.

Apparently children used to call it fireweed as it was the first thing to grow after bombs during the war. I am lucky enough to have loads of the stuff just next to the horsetails

midgey,

Don't put it on your compost heap either.

We have a "green bin" - actually it's brown! - to put garden rubbish in.