Bailey Arboretum in Lattingtown on Long Island grew from Frank and Marie Louise Bailey’s summer estate, Munnysunk, into a forty-two-acre public arboretum after their heirs donated it to Nassau County in 1968. Frank Bailey, a financier and horticulturist, shaped its notable collection of exotic trees by selecting plantings himself and importing specimens from France between 1916 and 1920. The grounds include landscaped areas, trails, ponds, a greenhouse, and the historic manor house, while later additions expanded its educational and public mission. Its living collections, champion trees, accessibility features, wildlife hospital, and ArbNet accreditation reflect both botanical significance and community stewardship.