Random Questions of Chromosomes

I have heard that roses can have 2,3, 4, 5, 6, or 8 sets of Chromosomes, and this effects it’s reproduction. But I would like to know if someone could please shed some light on the matter for me. How does this effect its reproduction? Will roses of different number of chromos not cross with others. Will a hexaploid cross with a diploid? And why is a rose with three chromos sterile? Which species of roses are which? I am so confused. Do roses always get one chromo from each parent? Or would tetraploids get 2 from each and so on…

And what is up with albas uneven meiosis?

Hmm…I can’t wait to learn all this great stuff.

Thanks a lot,


Gametes: pollen and ovules are half chromosome number so that adding them restore original number. Diploids have haploid gametes, diploid ones for tetraploids and so on. Except Caninae that have haploid pollen and polyploid, usually tetraploid, ovules.

As a rule needed are full complements that is sets of all 7 complementary rose chromosomes or multiples of to get viable gametes.

But Caninae, all species do split homologue chromosomes even and if available chromosome are uneven the plant is more or less sterile. Unpaired plants such as haploids, triploids, pentaploids usually have this problem.

Interspecies rose crosses compatibility is variable but rarely impossible even if hybrids from species with the same chromosome number are eventually sterile. Hexaploids do cross with diploids: it is a shortcut to get tetraploids that are easier to cross to other tetraploids.

About sources for chromosome number they were cited before in this forum the best being Modern Roses.