Poaceae are dominant are estimated to constitute 40.5% of the land area of the Earth, excluding Greenland and Antarctica. Grasses are also an important part of the vegetation in many other habitats, including wetlands, forests and tundra. The Poaceae are the most economically important plant family, providing staple foods from domesticated cereal crops such as maize, wheat, rice, barley, and millet as well as forage, building materials (bamboo, thatch, straw) and fuel (ethanol). Though they are commonly called "grasses", seagrasses, rushes, and sedges fall outside this family. The rushes and sedges are related to the Poaceae, being members of the order
Smallest organisms cetacean, which is also (as of 2006) the most endangered, is the vaquita. Male vaquitas grow to an average of around 135 cm (53 in); the females are slightly longer, averaging about 141 cm (55 in) in length. Duckweeds of the genus "Wolffia" are the world's smallest flowering plants. Fully grown, they measure only 300 µm by 600 µm and reach a mass of just 150 µg. Nanobes are thought by some scientists to be the smallest known organisms about one tenth the size of the smallest known bacteria. Nanobes, tiny filamental structures first found in some rocks and sediments,