rr means the plant has pure recessive trait & rr means the plant has pure dominant trait & a red flowered plant (rr) is crossed with a white flowered plant (rr) ->  a pure dominant red flowered plant is crossed with a pure recessive white flowered plant  a pure dominant red flowered plant is crossed with a pure recessive white flowered plant & if pure dominant organism is crossed a pure recessive organism , then the offspring will have a 100% probability of being heterozygous dominant ->  the offspring of the red flowered plant and white flowered plant will 100% be heterozygous dominant  the offspring of the red flowered plant and white flowered plant will 100% be heterozygous dominant & red flower is a dominant trait in some plant -> the offspring of the red flowered plant and white flowered plant will 100% be red