[shanzz]

What would be the phenotype of a plant that showed codominance

[Tryingtoplumb]

Phenotype refers to the manifestation of the genes i.e. how the organism looks. For example, a gene could give a gene "blue flower" phenotype. Genotype refers to the genetic makeup of the organism. Codominance is when neither genotype/phenotype is dominant and so you end up with a mixing of effects e.g. if you had codomiance between a gene that makes red flowers and another gene that makes white flowers, after a cross the resultant flower would be pink.