Oxalis acetosella
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/22244945@N00/3565234041/sizes/o/">graymalkn</a>
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.Flickr.com/photos/22244945@N00/3565234041/sizes/o/">Flickr.com</a>