Think of the Red being a male and the white flower a female.
The Red flower injects it's pollen aka DNA or genes or what have you, into the white flower carrier.
Your Red flower will be R, dominant (Large)
Your white flower will be w, recessive (small)
together this would make a Rw flower with most traits from the red flower and smaller ones from the white. Like splashing dots of white on red is an example.
You could draw a punnett square to show the 3 kinds of flowers a Rw+ Rw would make. You can refer to my example picture showing the 1st 2nd and 3rd. Kind of flower that can be made... RR , Rw and ww.
If you have any questions leave a comment :).
