Hordeum pusillum, also known as little barley, is an annual grass native to most of the United States and southwestern Canada.

[1][2] It arrived via multiple long-distance dispersals of a southern South American species of Hordeum about one million years ago.

[4] Hordeum comes from the Latin word horreō, horrēre "to bristle " and pusillum is the "nominative neuter singular of pusillus"- "very little, very small, tiny."

First described in 1818 by Thomas Nuttall,[5] Hordeum pusillum, also known as little barley, is an annual flowering plant native to the majority of North America, mainly the United States and southwestern Canada.

[5] The roots are fibrous, and the mark of a mature spikelet is when they turn a tan to brown color.

[7] Its habitat is in sunny locations on dry gravely soils, rock outcrops, roadsides, railroads, waste places, in grasslands, and on marsh edges.

Evidence for the earliest known cultivation in eastern North America was found at the Gast Spring site in what is today Louisa County, Iowa.

Large plots were required to produce adequate harvests due to the grain's small size.

In the southeastern and midwestern United States, however, domestication lasted through the Middle Archaic and protohistoric periods.