spike-rush
n (Plants) any perennial plant of the temperate cyperaceous genus Eleocharis, occurring esp by ponds, and having underground stems, narrow leaves, and small flowers
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014