This is a picture of a <i>Cyperus esculentus</i> plant (chufa or tigernut), it was taken from <a rel="nofollow" class="external free" href="http://www.uga.edu/rootandtubercrops/English/photographs/chufa.htm">http://www.uga.edu/rootandtubercrops/English/photographs/chufa.htm</a>, the authors grant permission to copy and use the image with the sole restriction of giving a mention to the photographer (in this case, dr. Stanley Kays) (see <a rel="nofollow" class="external free" href="http://www.uga.edu/rootandtubercrops/English/photographs/">http://www.uga.edu/rootandtubercrops/English/photographs/</a> for licensing).
Dr. Stanley Kays
Attribution
<a rel="nofollow" class="external free" href="http://www.uga.edu/rootandtubercrops/">http://www.uga.edu/rootandtubercrops/</a>