Magnolia macrophylla Michaux (Big-Leaf Magnolia) has the largest size simple leaf and flower of any North American tree. Its primary geographic range includes the southeastern U.S. In North Carolina, it is predominantly found in Gaston County, located in the western Piedmont region of the state. This geographic isolation from its more extensive range in more southern states probably represents a bottleneck effect after the last glaciation period. Data from eight population sites sampled from the 2000 to 2002 growing seasons show a significant correlation of M. macrophylla with more mesic habitats. Fagus grandifolia, Acer rubrum, Liriodendron tulipifera and Oxydendrum arboreum are important associate species within these sites. Periodic disturbance may be an important factor in the maintenance and establishment of M. macrophylla populations.