Macklin, J. A. (The Academy of Natural Sciences, 1900 Benjamin Franklin Parkway, Philadelphia, PA 19103; macklin@acnatsci.org), G. Moore (Brooklyn Botanic Garden, 1000 Washington Avenue, Brooklyn, New York 11225; gerrymoore@bbg.org) & J. C. Lendemer (The Academy of Natural Sciences, 1900 Benjamin Franklin Parkway, Philadelphia, PA 19103; lendemer@acnatsci.org). Typification of seabeach amaranth, Amaranthus pumilus (Amaranthaceae). Brittonia 57: 273–275. 2005.—Amaranthus pumilus is known from coastal Massachusetts to South Carolina and from ballast in Philadelphia, Pennsylvania. It is currently listed by the United States Fish and Wildlife Service as a threatened species. Amaranthus pumilus was originally described by Rafinesque in 1808 from southern New Jersey, but he did not cite specimens. Here, the name A. pumilus is lectotypified using the only known original element, a Rafinesque specimen at the herbarium of The Academy of Natural Sciences, Philadelphia (PH).