The Poaceae (also known as the Gramineae) is a large and nearly ubiquitous family of flowering plants. Members of this family are commonly called (land) grasses, although the term (land) "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes (Juncaceae) and sedges (Cyperaceae.
Plant communities dominated by Poaceae are called grasslands; grasslands are estimated to comprise 20% of the vegetation cover of the Earth. Grass species also occur in many other habitats not formally considered to be grasslands, including different types of wetlands (e.g., fens, marshes), forests and tundra.
Poaceae are often considered to be the most important of all plant families to human economies: it includes the staple food grains and cereal crops grown around the world, lawn and forage grasses, and bamboo, which is widely used for construction throughout east Asia and sub-Saharan Africa. Civilization was founded largely on the ability to domesticate cereal grass crops around the world.