Narcissus 2010

[Gerry Webster]

Anne - are they self-sterile (like Crocus cartwrightianus)? Have you tried pollinating with another species?

[Ian Y]

lease can someone explain how some plants, such as Narcissus Cedric Morris, can have fertile pollen but they will not set seed? Is it not the same process producing both the male and female gametes?

Anne I suspect that 'Cedric Morris' is a triploid. To cross or self fertilise half the chromosomes need to come from each parent and  dividing three by two does not give a whole number.
If a plant was to mutate again and say double its chromosomes to six then you will have a fertile plant.
I have tried using the pollen onto some other Narcissus without any success but there are not many in the same section in flower just now - I should save some pollen in the fridge.
How ever not being fertile means the flowers stay fresh for longer than any other Narcissus I know.

[annew]

The pollen is fertile - that's what puzzles me. I guess someone will say unreduced gametes if it is indeed a triploid. I've tried pollinating with all sorts, and it will not set seed. Daffnet also says it has fertile pollen only.

[Gerry Webster]

Although of no obvious help with Anne’s problem, it seems that  ‘Cedric Morris' is tetraploid.

In a recent study involving measurements of the amount  of nuclear DNA in Narcissus, it was found that  ‘Cedric Morris’ - here regarded as N. asturiensis subsp. villarvildensis  -   had 48 pg of DNA per nucleus. In comparison, 7 samples of N. asturiensis subsp. asturiensis were found to have an average of  24.2 pg per nucleus.

The investigation can be found here: ‘The systematic value of nuclear DNA content for all species of Narcissus L. (Amaryllidaceae)’ by B. J. M. Zonneveld.  In Plant Syst. Evol. (2008) 275:109–132]

[annew]

Ooops I've got that article, but haven't read it yet. If tetraploid, then it should be fertile both ways, shouldn't it?

[Martin Baxendale]

Please can someone explain how some plants, such as Narcissus Cedric Morris, can have fertile pollen but they will not set seed? Is it not the same process producing both the male and female gametes?

Anne, it's to do with the numbers - the odds of fertilisation. A triploid could set seed, but the chances are far lower than the chances of its pollen being successful in pollinating another plant.

If, for example, because of triploidy, a plant's gametes only had a fertility rate of one in a thousand, and if the average number of ovules in the seed pod was say 30 then there's little chance of any of those 30 ovules being fertile. And even if one was fertile and was pollinated, one or two fertilised seeds in one pod might not be enough to prevent the pod aborting. But if you take some pollen from the same plant, with hundreds of thousands of pollen grains, and put the pollen onto another (non-triploid, fertile) plant or plants, then out of those hundreds of thousands of pollen grains, even one in a thousand of them will add up to a lot of fertile pollen grains capable of pollinating a fertile ovule on another plant and producing seed.

[Gerry Webster]

Ooops I've got that article, but haven't read it yet. If tetraploid, then it should be fertile both ways, shouldn't it?

Yes, I think so.

[Martin Baxendale]

Ooops I've got that article, but haven't read it yet. If tetraploid, then it should be fertile both ways, shouldn't it?

Like Ian, I've never managed to get seed from Cedric Morris, but I have managed to pollinate cyclamineus with it, so I too thought it must be a triploid. If it was a tetraploid, then it should set seed freely if crossed with a fertile narcissus with which it's compatible, like cyclamineus.

[rob krejzl]

Some lines of tetraploid lilies (particularly LA's) produce small amounts of haploid gametes as well as 2N ones. If that is the case with Cedric Morris it might explain these observations.

[Regelian]

In Zonnenfelds work, he is not telling us the actual karyotype, rather the measured DNA.  If Cedric Morris has twice the amount of DNA, this doesn't necessarily mean that it is a balanced tetraploid.  It may be an alloploid with non-balanced chromosome sets.  This would make it difficult to have a perfect meiosis and most of the gametes would have incompatable chromosomes and thus be infertile.  A small percentage may be fertile and, as there is considerably more pollen than egg gametes, the chances are that we could use the pollen, while setting seed may be close to impossible.

This is just a thought, as I don't know the karyotype.  Cedric Morris may be a wild hybrid.

[Gerry Webster]

Jamie - I'm afraid I was rather careless in my reading of Zonneveld. He doesn't describe Cedric Morris as tetraploid but as having a "tetraploid amount of DNA" - not quite the same thing. I find your argument persuasive.

[annew]

Thank you everyone. I think I understand. More thought required. 

[annew]

This is a lovely narcissus, new to me - Narcissus romieuxii JCA805 Treble Chance.

[Gerry Webster]

It's not only lovely but very long lasting. The first flowers here opened on 22nd Nov & the pot still looks good. A superb plant & a tribute to Bob Potterton. Incidentally Anne, you managed to capture the colour much better than I did.

[David Nicholson]

Very nice.