Genetics Problem (rock roses)

Last summer my wife planted a bundle of “rock roses” along the sidewalk near the entry to our house.  All the plants had pink flowers and sprawling, branched stems. It was quite a scene in pink by the early fall! The plants are annuals and all died over the winter, but what a surprise this summer – dozens of plants came up from seed and the variety was very interesting. The greatest number of plants had pink flowers and sprawling stems like the ones we planted last year, but others had red flowers, some had white flowers, and there were all color varieties with sprawling and erect stems. Curious, I made a detailed count. These are my results:

pink, sprawling plants = 18
pink, erect plants = 6
red, sprawling plants = 6
red, erect plants = 3
white, sprawling plants = 9
white, erect plants = 3

I pondered the genetics of these plants for a while, but finally figured out what was going on.  Using R and r for the flower color gene, and S and s for the stem type gene, answer the following questions.

What Mendelian variation is happening with regards to flower color?

____________________   _____________________ (2 points).

What was the genotype of my wife’s original pink plants with sprawling stems?

 ________________________   (2 points)

Draw the “grid” (Punnet square) for the crosses that must have been going on last summer showing how I could get all the results I obtained above (4 points).

CIRCLE the white sprawling offspring in the Punnet square (2 points).