At October 15, 2009 Harold sent a photo to Daffnet of a flower from a cross ‘N. cavanillesii x N. viridiflorus’. He made this cross in 2003. In this year I did the same. Ten years later I got the flowers in the pictures. They have very good pollen fertility and I think seed fertility too, because they are allotetraploid. That means in this case they have two chromosome sets of N. cavanillesii and two of N. viridiflorus. Crosses with standard daffodils, allotetraploid jonquilla- and viridiflorus- hybrids and with many diploid species could be possible. Most of these crosses are probably not suited to the climate in Germany, but perhaps for the coast of the Netherlands and surely for regions with a mediterranian climate.
I never saw N. x xanthochlorus in Southern Spain, where I found many natural crosses of N. x perezlarae ( N. miniatus x N. cavanillesii) and N. x alleniae (N. miniatus x N. viridiflorus). These two are normally infertile. The fertility is a great advantage for N. x xanthochlorus, and it should have similar possibilities to spread out around the Mediterranean Sea as N. miniatus in the future even if it is scarce now.
For me it grows good like N. cavanillesii and N. x perezlarae, but all of them don’t like to flower. I hold the bulbs in pots in the glass house and dry during summer at 25 degrees C in a heat box without soil. What can I do to get more flowers? I have no problems to flower N. viridiflorus, N. miniatus and N. x alleniae under the same conditions.
I didn’t find N. x xanthochlorus in Daffseek. I think it should be introduced.