Several series of multiple alleles are known in corn. Two such series are briefly described.
C locus on chromosome 9. C locus on chromosomes 9 controls colour and has atleast three alleles including CI, an inhibitor of colour, O responsible for full colour in presence of A and R, and c expressing colourless phenotype. Sometimes they are also designated as CI, C and c. These alleles are also described to be closely linked genes, rather than alleles.
R locus on chromosome 10. This is a complex locus, controlling anthocyanin colour of seed and the plant. Following four alleles were earlier designated as Rr, Rg, rr, and rg. But later, due to
their two independent functions, they were
designated as SP, Sp, sP and sp respectively.