Quaking \Quak"ing\, a. & n. from {Quake}, v. [1913 Webster] {Quaking aspen} (Bot.), an American species of poplar ({Populus tremuloides}), the leaves of which tremble in the lightest breeze. It much resembles the European aspen. See {Aspen}. {Quaking bog}, a bog of forming peat so saturated with water that it shakes when trodden upon. {Quaking grass}. (Bot.) (a) One of several grasses of the genus {Briza}, having slender-stalked and pendulous ovate spikelets, which quake and rattle in the wind. {Briza maxima} is the large quaking grass; {Briza media} and {Briza minor} are the smaller kinds. (b) Rattlesnake grass ({Glyceria Canadensis}). [1913 Webster]