Full paper Selection of Double Flowers in Cultivated Roses

See:

Link: www.ncbi.nlm.nih.gov/pmc/articles/PMC2823793/

As I was sorting through old notes I came across an interesting related reference. Semeniuk noted that the old CV Ma Perkins is single at high temp, double at low, but with a constant number of flower parts. Conversion of stamens to petaloids is what’s going on.

I have noticed Crimson glory do somewhat the same, reducing petals to under 20 at high temps.

This may account for some cases of pollen being available in summer at higher temps. I know that’s true for one of mine, the cross of Carefree Beauty x Rise N Shine.