rattlesnake-grass

from The Century Dictionary.

• noun See slough-grass.
• noun An American grass, Glyceria Canadensis, a handsome stout species with a large panicle of drooping spikelets, which are ovate, and flattish but turgid, like those of Briza, the quaking-grass. It is a useful forage-grass in wet places. Sometimes called tall quaking-grass.