The forest type found at Sagamore Hill is deciduous, second growth oak-tulip (yellow poplar). Oak-tulip tree forests are mesophystic, hardwood forests occurring on well-drained soils throughout Southeastern New York. The park contains a notable 2-acre patch of oak-tulip tree forest in the northwest corner of the park that has remained predominantly free of exotic species. Such patches of intact forest are quite rare on Long Island, with only a single significant occurrence of this community existing in Nassau County.