Harisons Yellow from Margit Schowalter Canada

Margit sent me pollen of Harison’s Yellow. I measured 15 pollen grains, each 4 times. The pictures are given in the link below.

The average diameter is 32.6 with a standard deviation of 3.7.

She had also sent me pollen of Harison’s Yellow in July of 2008. Then, I looked at 10 pollen grains and obtained an average of 35.4 with a standard deviation of 3.9.

(David Zlesak reported a diameter of 38.4 with a standard deviation of 3.1. He classified it as a tetraploid.)

The large standard deviations and the appearence of 2 groups of pollen with different sizes strongly suggest (to me) that this is a classic example of a triploid (the following link shows 2 different sized pollen grains on one slide):

http://picasaweb.google.com/lh/photo/X68Oskcz0mIXT9MONDlwMA?feat=directlink )

Link: picasaweb.google.com/HAKuska/HarisonsYellowFromCanada?feat=directlink

Thanks Henry and David. I have been trying to use R. foetida and it close relatives a lot in breeding. Somethings they seem to set on well and other things everything fails. I like the idea of using them because they are hardy, drought resistant and many of the most unusual colors come from lines descended from them. I am a little worried about disease issues like black spot, but I do think blackspot in modern roses is not all R. foetida fault and a lot of bad decisions went into breeding a lot of the earlier yellows. I am not as interested in yellow as much as I am interested in mauves and lavenders. I find it interesting many lavenders and mauves descend from R. foetida, I do not know what to make of that, but I plan to explore it.

So Henry since this plant is most likely triploid I was thinking one could cross it to a diploid. Then the best offspring could be crossed together and maybe if one was lucky one could get a bright yellow diploid. Does that sound reasonable? I was hoping on using R. foetida persiana in a similar way. I did a few crosses this year towards that end. I do not know yet if those crosses took but it is hopeful at the moment.

Hi Henry,

The ‘Harison’s Yellow’ at the MN Landscape Arb that I worked with is tetraploid and since that manuscript there are other forms sold under the same name that Peter Harris has acquired and I have counted that are triploid. There are collections of ‘Harison’s Yellow’ from other places than the MN Landscape Arb that are tetraploid as well. I suspect as well you probably have a triploid form.