THE DISTRIBUTION AND HABITAT PREFERENCES OF RARE GALACTICA SPECIES (FABACEAE) AND CHAMAESYCE DELTOIDEA SUBSPECIES (EUPHORBIACEAE) NATIVE TOSOUTHERN FLORIDA PINE ROCKLAND

South Florida pine rockland is a species-rich forest type found on lim estone outcrops in southernmost Florida. The largest area of these for ests in Florida, occurring on the Miami Rock Ridge near Miami, origina lly covered 52,754 ha; today less than 6,174 ha remain. The destructio n of large areas of pine rockland has endangered many plant species. I studied the habitat preferences and distributions of four species of the legume genus Galactia P. Browne and three subspecies of Chamaesyce deltoidea (Engelmann) Small native to pine rockland. Two Galactia, G, pinetorum and G, smallii, and all three C. deltoidea subspecies are r are and restricted to pine rockland. The other two Galactia, G. florid ana and G. parvifolia, are widespread outside southern Florida. A stro ng soil gradient was found to explain the distribution of the endemic Galactia and Chamaesyce taxa and G. floridana, one of the widespread s pecies. This gradient represents a transition from acidic quartz sands to basic calcareous soils. Several other pine rockland endemic taxa a nd two invasive pest plants also responded to the soil gradient. Other factors correlated to endemic plant density were exotic plant cover, site elevation, and fire history. Exotic plant cover was greater in sm aller forest fragments.