culm vs sedge

culm

noun
  • the stem of a plant, especially of grass or sedge 

  • anthracite, especially when found in small masses 

  • waste coal, used as a poor quality fuel; slack. 

sedge

noun
  • Any of certain other plants resembling sedges, such as Gentiana rubricaulis and Andropogon virginicus. 

  • A flock of herons, cranes, or bitterns. 

  • A dry fly used in fly fishing, designed to resemble a sedge or caddis fly. 

  • Any plant of the genus Carex, the true sedge, perennial, endogenous herbs, often growing in dense tufts in marshy places. They have triangular jointless stems, a spiked inflorescence, and long grasslike leaves which are usually rough on the margins and midrib. There are several hundred species. 

  • Any plant of the family Cyperaceae. 

How often have the words culm and sedge occurred in a corpus of books? (source: Google Ngram Viewer )