What is this please?

This yellow flowering weed is growing in a pot on the wall among lobelia,came again from last yr, and ivy.I don`t mind it...would just like to know what it is.

 

meadow buttercup?
http://www.ryenats.org.uk/detail1.htm
I thought it looked like wild mustard but the flowers of that seem to be in clusters....

 

Cheers Liz.The birds must have brought it in.

 

Er.... Sorry to disagree, Liz - but it only has four petals, and buttercups have five. It's one of the "crucifers" which get their name of "cross-bearers" from the four-petalled flowers.

The piccie's a bit out of focus so the flowers aren't clearly shown, but my guess would be one of the common ones like Charlock. Don't know if you can post a photo showing the leaves, elainefiz - the ones at the bottom of the stem as well as the top - and maybe get a sharp image of the flowers?? (Does your camera maybe have a "close-up" setting?) Then we've got more chance of pinpointing the species.

 

anyone any ideas then

 

It looks almost like Rape that has been growing in a lot of the fields round and about these last few weeks,but as the photo is out of focus it is hard to pinpoint an exact identification

 

Evening, Kandy. It would only be rape if it is heady smelling ... I am terribly allergic to it ... another good reason to live here!

 

I finally found my book(hooray!)and i think it must be either Charlock (weed)or White Mustard.(cabbage family)The pics i`ve taken are worse than my first attempt so i`ll not bother to re post but it fits the books illustration-discription perfect to white mustard apart from 2 factors.The first being that it says, hairy below? and the second is it flowers june-oct.
Does, hairy below refer to the fruit?

 

Hi, elainefiz! My taxonomic key ("Excursion Flora of the British Isles", Clapham, Tutin & Warburg) tells me that all the leaves on White Mustard are lobed or partly cut into what look like leaflets, whereas Charlock has upper leaves without stalks and shaped like a spear point, but stalked lower leaves which are shaped more or less like a lyre. The leaves and stem on both plants are hairy...!

Does this help?!!!

Incidentally- something I didn't know - is that Charlock is also known as "Wild Mustard"! I'd heard of "White Mustard", but never "Wild"... so Liz and I were at least partly on the same wavelength after all! (But it can't be a buttercup!!)