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Incomplete Dominance

Multiple alleles
Chapter 7main
In incomplete dominance, there is not a single dominant or recessive trait observed.  Instead a combination of the two or a blending of the two traits is seen.  The classic example of such a system occurs in flower color in the Four O'clock flower.  This is a relative to the Morning Glory, a low growing ground cover seen in the mid to late spring. 

In the four O'clock flower there are two alleles A red allele that codes for a red flower and allele that codes for a white flower.  Red is not dominant to white nor is white dominant to red.  The only way for the trait to be seen is in a homozygous condition.  In other words, a red flower will sport the RR genotype (homozygous red alleles) and the white flower will done the WW alleles (homozygous white alleles).  If we are to be completely correct the white alleles should not be WW but rather R` R`, where R`= White.  Now when the heterozygous condition is seen, a mixing of the two colors is seen as a pink flower.