In the United States, the federal government uses the term endangered to refer to a species in danger of extinction throughout all or most of its range.

The term threatened refers to a species that is likely to become endangered in the near future.

The Endangered Species Act of 1973 (Act) is one of the most far-reaching wildlife conservation laws ever enacted by any nation. It is administered primarily by the U.S. Fish and Wildlife Service (Service), working in cooperation with other Federal, State, and local agencies, as well as independent organizations.

Over 600 species of plants and animals native to the United States and more than 500 species living in other parts of the world have been placed on the U.S. List of Endangered and Threatened Wildlife and Plants.

The listing process is one of the basic functions performed by the Service in carrying out its responsibilities under the Endangered Species Act. Once an animal or plant is listed, all protective measures authorized by the Act apply to the species and its habitat. Such measures include protection from any adverse effects of Federal activities, restrictions on taking, transporting or selling a species, authorization for the Service to develop and carry out recovery plans, and the authority to purchase important habitat.

The Decurent false aster (Boltonia decurrens) is an herbaceous perennial endemic to the Illinois River floodplain and Mississippi rivers. It is listed threatened.

The Missouri bladderpod (Lesquerella filiformis) is a tiny winter annual that is endemic to limestone glades in roughly 50 sites in four counties in southwestern Missouri. It is listed endangered.