(1977)  Page(s) Vol. 26, No. 3, pp. 703-708.  
 
Breeding for improvement of flowering attributes of winterhardy Rosa kordesii Wulff hybrids
Felicitas Svejda
G12 was obtained from open pollination of 'Max Graf' and a cytological examination by Dr D. R. Sampson, of this Station, found it to be tetraploid (2n = 4x = 28). G12 differs from R. kordesii in that it is very hardy at Ottawa where it shows little or no winterkill. It flowers non-recurrently and produces fewer flowers. It has single, pink flowers like 'Max Graf'. R. kordesii is regularly killed to the snow-line at Ottawa, it flowers recurrently and is more floriferous than G12. Unlike 'Max Graf, R. kordesii has double flowers.

The offspring from the cross of the recurrent R. kordesii with the non-recurrent seedling G12 segregated into non-recurrent and recurrent types in a ratio of 3:1 for a tetrasomic inheritance, assuming a duplex segregation and complete dominance.