vascular flora of Hoffman and Swinburne Islands, New York Harbor, New York1, The

Journal of the Torrey Botanical Society, Jan-Mar 2002 by Stalter, Richard, Munir, Affaf

RICHARD STALTER AND AFFAF MUNIR (Department of Biological Science, St. John's University, Jamaica, New York 11439.). The vascular flora of Hoffman and Swinburne Islands, New York Harbor, New York. J. Torrey Bot. Soc. 129: 77-82. 2002.-Hoffman and Swinburne islands, located 1.5km east of Staten Island, New York, were constructed in the late 19^sup th^ century from sand dredged from New York Harbor. The islands were deeded from New York City to the federal government in 1972; today they are part of Gateway National Recreation Area. The vascular flora of Hoffman and Swinburne Islands was sampled during the 2000 growing season, and in May and June, 2001. The combined flora of both sites (ca 5 ha) consists of 88 species, 72 genera, and 36 families. Thirty-six species occur at Swinburne Island, while 87 species occur at Hoffman Island, the larger of the two islands. The largest family in the flora is the Asteraceae (18 species). The largest genera are Artemisia Aster, and Potentilla each with three species. Non-native species, 63.0% of the flora, are a major component of the natural vegetation. The annotated list includes the island and locality in which each species occurs, the frequency of occurrence, and pertinent synonyms.

Key words: vascular flora, Hoffman Island, Swinburne Island, Gateway National Recreation Area, New York City, New York.

Hoffman and Swinburne Islands are both located in New York Harbor (40 35'N Latitude, 74 4' W Longitude) approximately 1.5 kilometers east of Staten Island, New York. Hoffman Island (4.0 hectares), the larger of the two islands, is located approximately 1 kilometer northwest of Swinburne Island (1.0 hectare) (Sietz and Miller 1996).

Hoffman Island was constructed in the mid 1860s from sand dredged from New York Harbor. Construction of the initial 1.0 hectare of this island was completed in 1873. The island, named for John T. Hoffman, mayor of New York City from 1866-1868, and governor, 1869-1872, was to serve as a quarantine island. Three two-story buildings were constructed to house immigrants exposed to, but not exhibiting signs of, contagious diseases; they were housed on the island during incubation periods that usually lasted from a few days to two weeks. As the need to house immigrants with contagious diseases increased, New York State enlarged Hoffman Island to 4.0 hectares in 1896 (Sietz and Miller 1996).

Additional buildings were erected on Hoffman Island in 1916. Existing buildings were repaired, and renovations continued from 1916 through 1923. After American entry into World War I in 1918, the island hospitals were used to house soldiers with venereal diseases. In 1921, new laws restricted immigration, and the need for the island as a quarantine center declined. After 1928, only three people were detained on the island. From 1931 to 1972, the island served as a parrot quarantine center (1931-1937), a picnic site (1938), and a Merchant Marine training facility (1938-1947). Additional plans for Hoffman Island from 1947 to 1960 never reached fruition.

In 1968, New York City razed the existing buildings and planted grass on the island. Plans to develop Hoffman Island as a New City Park were abandoned. Hoffman and Swinburne Islands were deeded back to the federal government in 1972 as part of Gateway National Recreation Area, a 10,522 hectare park, the country's first and largest urban National Park. The National Park Service's present plan for the two islands is benign neglect; vegetation has been allowed to grow unimpeded by saw, brush hog or mower. Both islands serve as nesting sites for cormorants and gulls. The copious guano deposition from sea birds may play a role in maintaining the present assemblage of vascular plants on both islands.

Swinburne Island, a one hectare island, is the smaller of the two islands. Swinburne Island was orginially named Dix Island to honor New York Senator Dix who served from 1845 to 1848. Dix Island's name was changed to Swinburne Island after the Civil War to honor Civil War hero Dr. John Swinburne, who was prominent in the development of the island's quarantine centers. Swinburne Island served as a quarantine center from the 1870s to the 1920s. Laws severely restricting immigration were enacted in 1921 and with the reduction of immigration, the need for an immigration quarantine station was severely reduced. With few detainees, Swinburne Island's role as a quarantine center ended in 1928. The island housed an electronic control center for the production of underwater mines during World War II. The site was decomissioned after the war and various proposals to revive the island never were brought to fruition.

In 1956, Robert Moses planned to unite Hoffman and Swinburne Islands by landfill to create a 100 hectare park. Nothing came of this plan, but city officials discussed using the two islands as a garbage disposal site connecting the two islands with Fort Wadsworth. When Staten Island citizens caught wind of the plan, people were outraged and the plan abandoned. In 1972, Hoffman and Swinburne Islands were deeded back to the federal government as part of Gateway National Recreation Area (Sietz and Miller 1996).