Serpentine loosely refers to a broad group of minerals associated with the weathering of ultramafic (high iron and magnesium-rich) rocks found along continental margins and orogenic belts. Soils associated with such rocks often differ from more widespread soils, being less fertile and having high concentrations of some heavy metals. The unique geochemistry of serpentine soils generates habitats worldwide that are biologically unique, providing model settings for research on how geology and soils can shape the biotic world around us. Serpentine outcrops worldwide are known to harbor high rates of plant endemism (Brooks 1987, Kruckeberg 2002). For example, of the 1410 plant species endemic to California, 176 (12.5%) are restricted to serpentine (Safford et al. 2005), a substrate covering less than 1.5% of the state. This number is remarkably high given only 669 taxa are associated with serpentine soils in California. Thus, it is no surprise that serpentine floras are well-studied in California and other parts of western North America (Alexander et al. 2007, Harrison and Viers 2007), not only for their taxonomic value but also for their usefulness in testing ecological and evolutionary scenarios. Additional examples include the tropical islands of New Caledonia and Cuba, which also provide remarkable cases of serpentine endemism (Boyd et al. 2004, Brooks 1987, Kruckeberg 2002). In New Caledonia, 3178 taxa, approximately half the native fl ora, are endemic to serpentine soils (Jaffré 1992). In Cuba, 920 species, approximately one-third of the taxa endemic to Cuba, are found solely on serpentine soils (Borhidi 1992). Similar restrictions and notable floristic associations are also found in serpentine areas of the Mediterranean,
