Two populations of Funaria flavicans, were grown on nutrient media varying in Ni and Cr concentration and in the ratio of Mg and Ca. There was no evidence that serpentine plants were more tolerant of Ni, Cr, Mg/Ca, or high Ni combined with high Mg/Ca. Plants from the nonserpentine population produced more protonemal growth than the serpentine plants on every medium except the control, on which plants from the two populations were indistinguishable. Large differences in Ni tolerance among haploid sib families (families of meiotic progeny derived from the same sporophyte) from the nonserpentine site provided evidence of genetic polymorphism in that population. -from Author