This globally rare annual of dried shores occurs mostly on the Atlantic Coastal Plain. The degree of rarity and threat for this species remains uncertain. Although records are widely scattered and sometimes locally common along artificial impoundments,, probably with long-lived seed banks, there are only about 200 colls. in total (SERNEC). F. perpusilla is a remarkable, diminutive diploid (2n = 10) relative of vahlii and annua, reaching no more than 8 cm in height. It has recently been discovered on mudflats of the artificial Honker Lake in TRIG (Boone & Chester 2009; see APSC), which extended its known range 150 miles west from the Cumberland Plateau of Tenn. There may also be a record from BALL, as mapped by K (Dec 2020). During the 1980s, it was found on the eastern Highland Rim at Rowe Gap Swamp in Franklin Co., Tennessee (Wofford & Jones 1988); and during 2010, a large population was found by D. Webb on the western Highland Rim along the "Kentucky Reservoir" (impounded Tennesee Rv.) in Benton and Humphreys Cos. (SERNEC). There is also a single 1897 record from Butler Co. in se. Mo. (Diamond 2016). Further south and east, mostly in three disjunct clusters on the Coastal Plain from Ala. to Del., there are only about 18 counties with records (K, SERNEC).