Eleocharis acicularis
 
Needle Spike-Rush

Achene Close-Up

Highway # 9 at Overflowing River, North of Hudson Bay, SK
31-August-2017

There are 8 to 12 longitudinal ridges connected by longitudinal rows of short horizontal ridges call trabeculae.  Note the scale; the achene is very small.  This picture was taken with a trinocular microscope.  The setup is shown below.  The achene is the white speck just below the "9" on the ruler. All other pictures of this species were taken with a 60 mm macro lens.