The sandplain gerardia (Agalinis acuta) inhabits dry, sandy, poor-nutrient soils in sandplain and serpentine sites in Massachusetts, Rhode Island, Connecticut, New York and Maryland . Its favored growing conditions are native grasslands on sandy loam, loam and loamy sand soils. It requires exposed mineral soil in close proximity to little bluestem and other native grasses, with which it is thought to form hemiparasitic root connections . Most sites are within ten miles of the coast. The taxonomic relationship between A. acuta and the non-endangered A. tenella is unclear. They are morphologically distinct, but chloroplast DNA variation is not significant .
Fifty-one populations were known historically (two more than reported in the 1989 federal recovery plan), but only 12 remained when the gerardia was placed on the endangered species list in 1988 (two more than known at that time). Reintroductions increased the number of occupied populations to 22 in 2005. Short-term population trends can be misleading because of the species' capacity for explosive population growth and rapid decline. Populations in all states except Rhode Island grew substantially between 1988 and 2005. Massachusetts, Connecticut and New York populations were stable to moderately increasing between 1988 and the late 1990s, increasing significantly in the late 1990s and early 2000s, growing explosively for one or several years, then rapidly declining in 2004 or 2005. There are indications of a similar pattern in Maryland, but adequate data are not available. The small Rhode Island population fluctuated substantially with an overall stable trend. Cumulatively, the MA, RI, CT and NY populations increased dramatically from means of 4,441 (1988-1993) to 14,069 (1994-1999) to 196,466 (2000-2005).
MASSACHUSETTS. The sandplain gerardia historically occurred in 24 populations on Cape Cod, Nantucket, Martha's Vineyard and a few disjunct populations as far west as Worcester County . Its decline was so complete that it was thought extinct in the state until rediscovered on Cape Cod in 1980. When placed on the endangered species list in 1988, just two populations were known in historic cemeteries in Sandwich and Falmouth . A third population was discovered on Martha's Vineyard in 1994 . Due to intensive management, including scientific research, reintroductions, habitat protection and habitat management, the Massachusetts population grew remarkably. From 1988 (when it was listed as an endangered species ) to 1991 it declined from 13,977 plants to 150, steadily increased to 23,161 in 1998, then exploded to about 483,530 in 2004, before declining to about 49,063 in 2005. The 2005 decline is believed to be drought related .
The Sandwich population fluctuated greatly, but increased significantly between 1988 (9 plants) and 2005 (2,299) . High points were in 1995 (4,253), 2000 (4,757) and 2003 (3,712). The population only dipped below 1,000 plants twice between 1993 and 2005. The Falmouth population was discovered in 1981 and supported 6,994 plants in 1988. It was augmented with an introduced subpopulation on an adjacent site beginning in 1989. It declined to less than 50 plants in 1991 and 1992, steadily increased to 4,476 in 1999, exploded to 231,600 in 2004, then plummeted to 21,262 in 2005. A third natural population was discovered on Martha's Vineyard in 1994. It increased steadily from 378 in 1994 to 1,315 in 2000, then jumped to over 4,200 in 2002-2004, before declining to 1,309 in 2005.
Three populations were introduced in 1998 and 2000 . The Falmouth population increased steadily from 552 plants in 1998 to 15,000 in 2004, then declined to 1,910 in 2005. One Martha's Vineyard reintroduction increased from five plants in 1998 to 1,092 in 1994. A second Martha's Vineyard reintroduction increased from 23 plants in 2000 to 1,238 in 2003. Prior to these successes, there were "several" failed reintroduction attempts on Nantucket and a "couple" on Martha's Vineyard . Introduced populations, including the Falmouth subpopulation, often made up 40-50% of the total state population in the last decade.
RHODE ISLAND. The sandplain gerardia historically occurred in six populations in Rhode Island, but by 1988 was reduced to just a single population of 56 plants in a historic cemetery . The population fluctuated considerably, but without discernable trend between 1988 and 2005 . A second population of 33 plants was established in 2003 and grew to 241 plants in 2005.
CONNECTICUT. By 1988, the sandplain gerardia was extirpated from the only two known sites in Connecticut , but a very small population was discovered in 1990 . It fluctuated between zero and 32 observable plants from 1990 to 2002, then due to better site management, increased to 165 plants in 2004 before declining to 84 in 2005.
NEW YORK. The sandplain gerardia formerly occurred in 17 populations in New York . The Montauk, Long Island population alone was said to have once had "untold millions" of plants . At the time of listing, only six populations remained in New York with a total population of 814 plants . Cumulatively, the populations remained relatively stable until 1997 (approx. 500-2,000 plants), grew substantially through 2002 (7,272 plants), exploded to 83,531 in 2003, and declined to 10,488 in 2005. Reintroductions were attempted at seven locations after 1988. Of these, four were successful with a mean of 96-263 plants. Plants sown at new introduction sites, and at unoccupied locations within existing sites, accounted for 61-94% of total plants in New York 2001-2005.
MARYLAND. Maryland supported two historical gerardia populations, one of which was destroyed by urbanization and highway construction prior to 1988 . At the time of listing, a single population of 150 plants existed at Soldiers Delight Natural Environmental Area within Patapsco Valley State Park. The population has not been augmented, but due to an active program of burning, clearing, mowing and eradication of exotic plants, the Soldiers Delight population increased to 10,000 in 1989 and well over 100,000 "recently" . More detailed annual population estimates are not available, but the population presumably fluctuated significantly between these extremes. The Maryland Department of Natural Resources describes the population as stable or increasing, but cautions that additional monitoring is needed to establish a scientifically defensible trend . A second potential population was discovered at Andrews Air Force Base in 1993 but could not be relocated in 1995 . However, specimens could not be distinguished from A. obtusifolia and A. decemloba and thus may not be the sandplain gerardia.
The 1989 federal recovery plan  requires 1) The establishment or discovery of 20 stable, wild populations located throughout the species' historic range. To be "stable," a population must have a continuous five-year geometric average of at least 100 plants. 2) At least 15 of the populations must be on protected lands. 3) There must be proven technology for propagation or seed storage. As of December 2005, 13 populations had a five-year mean of at least 96 plants.
 U.S. Fish and Wildlife Service. 1989. Sandplain gerardia (Agalinis acuta) recovery plan. Newton Corner, MA. 47 pp.
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 Somers, P. 2005. Agalinis acuta data summaries, 1980-2005. Spreadsheets provided by Paul Sommers, Natural Heritage & Endangered Species Program, Massachusetts Division of Fisheries & Wildlife, Westborough, MA, November 2005.
 Somers, P. 2005. Personal communication with Paul Somers, Natural Heritage & Endangered Species Program, Massachusetts Division of Fisheries & Wildlife, Westborough, MA, November 17, 2005
 Raithel, C. 2005. Personal communication with Christopher Raithel, Rhode Island Division of Fish and Wildlife, Endangered Species Program, Providence, RI, November, 2005.
 Murray, N. 2005. Personal communication with Nancy Murray, Connecticut Department of Environmental Protection, Wildlife Division, November 22, 2005.
 Thomas, J. 2004. Endangered Plants of Maryland: Sandplain Gerardia. Maryland Department of Natural Resources website (www.dnr.state.md.us/wildlife/rtesandplain.asp) dated 10-25-04.
 Tyndall, W. 2005. Personal communication with Wayne Tyndall, Maryland Department of Natural Resources, Annapolis, MD, November 23, 2005.
 Davidson, L. 2005. Personal communication with Lynn Davidson, Maryland Department of Natural Resources, Annapolis, MD, November 28, 2005.
 Jordan, M. 2005. Agalinis acuta monitoring data, Long Island, New York. Spreadsheet provided by Marilyn Jordan, The Nature Conservancy, Cold Spring Harbor, New York, November, 2005
 Neel, M.C. and M.P. Cummings. 2004. Section-level relationships of North American Agalinis (Orobanchaceae) based on DNA sequence analysis of three chloroplast gene regions. BMC Evolutionary Biology 4:15.
 Jordan, M. 2006. Personal communication with Marilyn Jordan, The Nature Conservancy, Cold Spring Harbor, NY, February 13, 2006.