nut grass

noun
  1. either of two sedges, Cyperus rotundus or C. esculentus, that have small, nutlike tubers and are often troublesome weeds.

Origin of nut grass

An Americanism dating back to 1765–75
Also called nut sedge.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018