Looks like Mint to me!

Try crushing a leaf and smelling it and report back...Tg

It's mint, and is very invasive.

Could it be loostrife? My mint hasn't emerged yet but the loostrife has and its very invasive.

If it's all over your garden you probably don't want it! Someone may have planted it but if it spreads like that you're better off without it unless you have a very large area to fill up quickly.
Could it be a form of oregano? I have one like this that gets around a lot.

Looks like mint to me and if it is its no good pulling it up as you will get even more, it has to be dug up an the roots/runners removed.

Try crushing a leaf and smelling it. If its loostrife it won't smell much. Oregano and mint smell strong but different. None are really weeds but do spread as you have found!

Mint or oregano. Very similar leaves. A quick squeeze will tell you which.

i thought lysimachia punctata, but i can see why you think mint, though the leaves on mine are more serrated.

I'm glad you said that, SBG, I don't think it is mint. I'd have said lysimachia, too.

Thats the Latin name for loostrife isn't it?

Er, yes, Cammomile, now you mention it, I think it is.

So JB CROSS You have three suggestions.

Mint,oregano or loosestrife. Have you been out and squeezed it yet to eliminate the herbs.

I thought Loosestrife's proper name was Lythrum.

On reflection I think the subject plant could well be Loosestrife / Lythrum because of the timing of its appearance, and I have found it to be a colourful plant often found in the wrong place!

In other words .......a weed! :o))

Lysimachia is Loostrife and Lythrum is Purple Loostrife - confusing or what? The tall yellow flowered one that spreads everywhere is Lysimachia.

Thanks Steragram,

I get the purple variety popping here and there in my garden,hence my reply,I didn't know there was a yellow variety so you live and learn.

That's the beauty of forums like these, I often wonder where I would be, had I had a facility like this when I started gardening.

Yes it can be a bit confusing,and even more so when the experts reclassify plant names you have lived with for years.

But I don't think I will ever change, I am bit too set in my ways to change now, even if it means I get it wrong through such changes.

I didn't know the purple one spread itself around too. I did try to grow some once but think that garden was too dry for it.

I used to have big clumps of yellow Lysimachia growing in my garden, and although it was rather beautiful, I had to speak severely to it on several occasions when it got a bit pushy and crowded out other, more retiring plants.