The  four  o'clock  plant  possess  either white, green, or variegated
   leaves.  Inheritance  is uniparental: leaf color is determined only by
   the phenotype of the ovule source.

   For  example,  if  the  seeds  were derived from ovules of plants with
   green leaves, all progeny plants bore only green leaves, regardless of
   the phenotype of the source of pollen.

   This  inheritance is transmitted through chloroplasts in the cytoplasm
   of  the female parent, since the pollen is tiny and contributes little
   cytoplasm to the zygote.