Sven Zacek / Wood sorrel (Oxalis acetosella) flowers, Southern Estonia.

Sven Zacek / Wood sorrel (Oxalis acetosella) flowering on forest floor of boreal forest. Tartumaa, Southern Estonia. May.

SCOTLAND: The Big Picture / Wood sorrel (Oxalis acetosella) leaves at base of tree in ancient Ash (Fraxinus excelsior) woodland in spring. Rassal Ashwood National Nature Reserve, Highlands, Scotland, UK.

Andy Sands / Wood sorrel (Oxalis acetosella) two flowers after a rain shower, Suffolk, England, UK, April

Konrad Wothe / Common wood sorrel (Oxalis acetosella) and fern, Bavarian Forest National Park, Germany, May.

Robert Thompson / Wood sorrel (Oxalis acetosella) Co. Armagh, Northern Ireland.

Juan Manuel Borrero / Carambola or Starfruit (Averrhoa carambola). Mexico

Ernie Janes / Bank of Oxeye daisies (Oxalis sp) and Bluebells (Hyancinthoides) in which major gas pipeline runs Norfolk, UK, May.

Alex Hyde / Wood sorrel (Oxalis acetosella) growing on woodland floor. Plitvice Lakes National Park, Croatia. November.

Tony Phelps / Yellow-eyed sorrel (Oxalis obtusa) DeHoop Nature Reserve, Western Cape, South Africa.

Chris Mattison / Creeping wood sorrel (Oxalis corniculata) flowers. Derbyshire, England, UK, September.

Fabrice Cahez / Common wood sorrel (Oxalis acetosella) leaves, Vosges, France, May.