Rosa kordesii

Rosa kordesii, or Rosa × kordesii is a type of rose that arose naturally from hybridization followed by chromosome doubling. A hybrid between R. rugosa and R. wichurana was created called Rosa 'Max Graf', but it was diploid and nearly sterile, producing flowers but no fruit. This rose produced a few viable seeds as a result of self-pollination, and the seedlings that resulted were tetraploid instead of diploid, i.e., the chromosomes of both pollen and egg cells had been naturally duplicated. The tetraploid seedlings are amphidiploids.[1] A selection with double deep pink flowers and repeat bloom, also called 'K01 AgCan' was released by W. Kordes' Söhne in 1951.[2]


These tetraploid roses interbreed readily with one another, but not with their diploid ancestors. Under the biological species concept, a new species name Rosa kordesii was created for the tetraploid hybrid roses and their descendants.[3]


Amphidiploid roses can also be created deliberately from diploid-diploid hybrids by using colchicine spray on the growing tips of the plants. That strategy gives few successes, however, because the plant tissue has various chromosome numbers in different cells.[1] Amphidiploid roses including Rosa kordesii have been used to some degree in breeding programs in combination with naturally occurring tetraploid roses.[1]
https://en.wikipedia.org/wiki/Rosa_kordesii