There are two subspecies, ssp. siculum with greenish-red tepals and ssp. bulgaricum with greenish-cream tepals, often tinged pink. All mine are the redder subspecies.

Neither of those are green and white, without any sign of red in them though.

I noticed an expensive all white one in Bloms catalogue. but cant remember its name and I'm at work at present.
I will have a look tonight and get back to you.

Searched the Interweb thingy. I cannot find a white/green version of this on sale anywhere.

When I checked my catalogue it is a bright pink N. tripedale and £17.60 each Ouch!!

sorry to mislead you.

The bulb folks I showed the picture to are getting quite excited about it. Trouble is I spend more time removing these things rather than propagating so I am not sure how one goes about it.

Tie a bit of thread around the stem and when they have finished flowering lift the clump. follow the stem with the thread down to the bulb, then at least you have isolated that one. re plant/pot and see if it does the same next year. if it does you might be on to a fortune :o)

Trouble is that it is growing up through a rather delightful Gemu Helicopter which I would rather not destroy. There is also a normal flowering bulb right next to it.
Will give it a go.
As to a fortune, our friend who has PBR on a Geranium is waiting for it to stop costing her money after 10 years on sale.

I did wonder which geum it was Owd.
wait till later them you might lift the geum and split that too. :o)