The pattern and concentration of component alkaloids in wildtype and mutant genotypes homozygous for the alleles pauper, exiguus and nutricius in L. albus have been determined. Alkaloid production in geno-types homozygous for identical and complementary alleles have been determined. The study has revealed at least two alleles possessing different effectiveness in reducing alkaloid levels at the pauper locus, and the frequency distribution of alkaloid concentration in F2 indicates dominance of the high-alkaloid allele is incomplete. Seven alkaloids were identified in the wild-type genotype, of which four were found in all homozygous mutant genotypes in approximately similar proportions. The mutations identified by means of the Dragendorff reaction appear to affect a common substrate without affecting the amount of the different component alkaloids that are produced.