Hi Roma, I think this photo is very interesting.
Over the past week or two I have been wondering 'how is it that snowdrops with such varied flowering times can belong to the same species'? There are forms of several species (reginae-olgae, elwesii, plicatus) that flower months apart in the garden and so I wondered if there were hidden species that are reproductively isolated by flowering season. I did a bit of reading and this article was very helpful, emphasising that wild populations vary continuously according to genetics and environment:
https://www.revolution-snowdrops.co.uk/galanthus-reginae-olgae-part-i/
Also your photo shows that individual forms can vary quite a lot in flowering time (of course things move slower in winter, with individual flowers sometimes lasting for weeks).
Interesting article, Tristan. I think my G. corcyrensis are all one clone. I see seed capsules sometimes but I'm not sure if any survive marauding slugs to germinate. I t seems that position has a lot to do with flowering time. The ones in the front garden in full sun and well drained flowered right through November and into early December. The ones in the back garden are shaded by the house but not overhung by trees and get very little sun if any when the are above the ground and most are shaded by a large Hosta when dormant. They started flowering in mid December and are still flowering though rain and frost and a short spell under snow have left them a bit bedraggled. I notice some have botrytis so will have to dig them up when the frost goes.