Do you want to know for sure that you have identified that plant correctly?

You will need to pick up the illustrated companion to Gleason and Cronquist’s “Manual of Vascular Plants of the Northeastern United States”.  Its only $125 and if you buy both as a set, combined they will set you back $150. 

Its the only way I know how to id those sedges. If you have an interest in local botany, this is essential for your book shelf.

http://nybgshop.org/Illustrated-Companion-to-Gleason-and-Cronquista-s-Manual-of-Vascular-Plants-p-18432.html