Genetic diversity in three genera of perennial plants found in the sand pine, oak scrub in peninsular Florida was examined by allozyme electrophoresis. These plants vary greatly in terms of geographic range, population size, pollination ecology, and seed dispersal mechanisms.Ceratiola ericoides(Empetraceae) is a shrub that occurs throughout scrub and other sandy habitats in Florida and neighboring states. In contrast,Eryngium cuneifolium(Apiaceae) is a Federally endangered herbaceous perennial, limited to the southern end of the Lake Wales Ridge, site of a proposed National Wildlife Refuge that would be the first designed primarily to protect plant diversity. Four species of endangered woody perennialDicerandra(Labiatae) are part of a monophyletic group endemic to Florida sand pine scrubs;Dicerandra frutescensandD. christmaniiare found on the southern end of the Lake Wales ridge,D. cornutissimais found in north‐central Florida, andD. immaculataoccurs in a small area along Florida's Atlantic coast. Allozyme electrophoresis of 17 loci forC. ericoidesindicated that 64.7% of the loci were polymorphic (Ps), that there were 2.55 alleles per polymorphic locus (APs), and that the mean gene diversity (Hes) was 0.141. The proportion of genetic diversity among the four populations (GST) was 0.059. For the 31 loci analyzed inE. cuneifolium, Pswas 32.3%,APSwas 2.1, andHeswas 0.104.GSTwas 0.106. The woodyDicerandraspecies complex (four species) was analyzed for 17 loci.Pswas 64.7%,APswas 3.1, and mean gene diversity was 0.219. The meanGSTvalue across the species complex was 0.137. Taken together these results suggest that considerable genetic variation is still present in the relict populations of the rare scrub taxa (EryngiumandDicerandra), but that to preserve current levels of genetic variation will require protecting areas in each of several different scrub regions along a 350‐km stretch of peninsular Florida.