looks like oxalis.

Maybe O. griffithii?

Oxalis, can be rampant, i usually pull it out.

I don't think its griffithi, which I think has reddish sepals. I thought at first it was the common wood sorrel, but have never seen an oxalis with those trumpet shaped flowers before.

Stera think they all have those flowers dont they?

The flowers of most species stand more upright, and the flowers open farther, giving a star-like appearance, though they are actually bell-shaped to trumpet-shaped. On this one the leaflets aren't pointed enough to be a plausible O. regnellii, but the flowers match well. Hmm...I'll keep looking! : )

If it helps, I seem to recall that they close their leaves together at night. Thankyou for the replies so far...keep 'em coming please.

It certainly looks like ground sorrel, but with a bit of bellbind coming through? Two plants mixed in?

Yes Tug, that's what I meant - the ordinary wood sorrel flowers do open out much flatter than these.Not quite the same, Grandmage.
Mebian all the oxalis do this as far as i know.

Hi everyone, many thanks for all you answers.