What is the name of the broad expanse of flat land in the western United States and western Canada  where the species of plant called the Polygonum sawatchense of the buckwheat family be found?
Great Plains The Great Plains (sometimes simply "the Plains") is the broad expanse of flat land (a plain), much of it covered in prairie, steppe and grassland, that lies west of the Mississippi River tallgrass prairie states and east of the Rocky Mountains in the United States and Canada. It embraces
Eriogonum argillosum Eriogonum argillosum is a species of wild buckwheat known by the common names clay buckwheat, clay-loving buckwheat, and Coast Range wild buckwheat. It is endemic to California, where it is known only from San Benito and Monterey Counties. It grows on clay substrates, often of serpentine origin. This is an annual herb up to 30 to 60 centimeters tall with a basal patch of oval-shaped, woolly leaves and a naked stem. The top of the stem is occupied by the inflorescence, a cyme with several clusters of tiny white or pink flowers.