Weed of the Week

This is Creeping Woodsorrel, Oxalis corniculata, a tiny plant that hugs the gaps in our walls, stone and concrete.  Just about uniquely, the leaves are heart-shaped.  It's edible, with a pleasant tip-of-the-tongue sharpness (I tried it this morning). And, I'm told by You Tube, it demands a high price in posh restaurants.  Special teams of OCD foragers, even as I write, are combing the cracks in London pavements.  Tread softly, because you tread on my lunch.