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American Hart's-tongue fern Listed: 7/14/1989 Status since listing: Declined The American Hart's-tongue fern (Asplenium scolopendrium var. americanum) generally grows in steep, sheltered locations on calcium-rich soil of talus slopes with a north to northeast aspect beneath a hardwood tree canopy [1]. Fronds unfurl early in the spring, achieving much of their yearly growth before the overstory leafs out, closing the canopy. The Hart's-tongue fern was placed on the endangered species list in 1989 due to historic declines and threats of continued habitat loss, trampling, and encroachment by the invasive swallow-wort (Cynanchum rossicum) [2]. Disjunct natural populations occur along the Niagara Escarpment in New York, Michigan and Ontario, and in Alabama and Tennessee. An introduced population occurs in New Jersey [2]. The majority of plants occur in Ontario [5]. About 92% of U.S. plants occur in New York [1]. ONTARIO (stable): The great majority of plants and colonies occur in Ontario, Canada [5]. There are 100 historic colonies, of which 72 are thought to still exist, though all 72 have not been recently surveyed. Colony sizes range from several plants to between ten and a hundred thousand. About half of the extant colonies occur on public lands. The Canada population as a whole is believed to be secure and stable. MICHIGAN (stable?): Seven colonies occur in Mackinac County and one in Chippewa County [4, 6]. Two colonies of several hundred plants each are owned by the Michigan Nature Association. A nearby colony occurs on private land. Four colonies occur on the Hiawatha National Forest. The Chippewa County site was thought to have been extirpated by collectors in 1975, but two immature plants were observed in 1979 and one plant was seen in 1988 and 1992.NEW YORK: (declined). Ninety-two percent of known U.S. plants occur in 17 colonies in Onondaga and Madison counties, New York [1]. One of the colonies, Rock Cut Gorge, appears to be extirpated, as no plants were seen during surveys between 1989 and 2002. The last observation was of four plants in 1988. Counts of mature-plus- NEW JERSEY (unknown): A population of New York plants was introduced to New Jersey in the 1930s and continues to exist [7]. TENNESSEE (stable): There are two extirpated and one small existing population in Tennessee [3, 4]. The first Tennessee population was discovered in 1849 at the entrance of a cave west of Post Oaks Springs in Roane County but was extirpated by 1900, probably by collectors or accidental trampling by recreationists [3]. A second population at Grassy Cove near Crossville was extirpated, probably by a forest fire in 1927 or 1928. The sole remaining population was discovered in 1879 in a 30-foot wide, 75-foot long, and 75-foot deep sinkhole near South Pittsburg. The population was estimated at 200 in 1898, 110 in 1900, 58 in 1911, and 26 in 1929. The south slope of the sinkhole is thought to have collapsed between 1911 and 1929, killing a portion or possibly all of the population. Spores from Canadian plants were introduced in about 1929. Six plants were observed in 1930, two in 1934, and 26 in 1935. There were 17 plants in the late 1970s, one or two in 1991, two or three in the late 1990s, and five in 2004. It is not known how many are of native origin. Plants observed in recent years have been stunted and failed to produce spores. Spore production may have occurred in 1994, but has not been documented since the early 1980s. ALABAMA (declined): There are two existing populations in Alabama. The Fern Cave National Wildlife Refuge population, Jackson County, was estimated at 20 plants in the late 1970s, nine in 1981, four in 1990, three in 1993-1994, and none in 2004 [3, 4]. The Peterson's Pit population, Morgan County, occurs on private land 25 miles away [4]. It was considered vigorous and healthy, with 97 plants in 1981. The population declined to about 50 plants in 1989, 39 in 1990, and 33 in 1993-1994 [3, 4]. PROPAGATION (AL): Spores were collected at the two Alabama sites in 1993-1994, and in 1995, the first plants with fronds were produced from germinated spores collected at the Morgan County site [3]. In 1998, however, a broken irrigation hose flooded the plants in the greenhouse and all were destroyed. In 2004, the Tennessee Division of Natural Heritage contracted with the Center for Research of Endangered Wildlife at the Cincinnati Zoo and Botanical Garden to again research the possibility of spore banking (long-term cold storage of spores using liquid nitrogen) and tissue culture propagation. Spores and leaf-tip tissue were collected from the Morgan County site. The tissue culture propagation using the leaf-tip tissue was not been successful, but the spores showed vigorous germination. Currently they have several immature plants. PROPAGATION (NY): There has been some success in propagating and transplanting plants from the northern populations in New York [3]. [1] Kelsall, N., C. Hazard and D.J. Leopold. 2004. Influence of climate factors on demographic changes in the New York populations of the federally-listed Phyllitis scolopendrium (L.) Newm. var. americana. Journal of the Torrey Botanical Society |
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