The subject of this report has fascinated me for as long as I can remember. Soon after my grandparents (in 1930) acquired a cottage on the Straits of Mackinac, west of Mackinaw City, the dim red blinking beacon of the lighthouse seemed to call from 8 miles across the water, on uninhabited St. Helena Isalnd not far from the mainland of Mackinac County. Great rising plumes of smoke from a fire on St. Helena in the mid 1950s were visible from the cottage window. In 1958, Prentiss M. Brown, Jr., who had held an undivided two-thirds interest in St. Helena since about 1920, kindly granted me permission to botanize on the island, but not for 10 more years was it possible actually to set foot there for initial botanical exploration (thanks to a friendly boat-owning Mackinaw neighbor, John W. Childs). In the summer of 2001 this island was acquired as a nature preserve by the Little Traverse Conservancy, financed by private donations. So it is timely to present a botanical inventory–a work long in progress, particularly for the benefit of visitors to the island.