I have added the reference but have not added the parentage because of the comments on file between Cass and Robert. I have searched my computer for an ‘Ulster’ polyantha. No ‘Ulster’ poly was listed in Dickson’s 1914 catalogue. Neither ‘Ave Maria’ nor ‘Ulster’ (poly) was listed in Dickson’s 1938-9 catalogue. My best bet of the parentage would be ‘Ulster Gem’, 1917 a white single HT which flowered in clusters.
I received this rose from Vintage Gardens 4-30-2014. This lovely rose turns off-white with a bit of age, and has a wonderful rose scent, the color and size of bloom reminds me of Hybrid Musk Penelope. The dark shiny green leaves are small, there are tiny prickles under a few of the leaf joints. The plant canes are flexible and well branched, and there are numerous buds waiting to open.
The parentage is from Modern Roses 12. It is likely that Ulster is a different Ulster from the HP. Neither is mentioned in the American Rose Annuals of the period.