Several years ago, my mum and I raised several plants of Oenothera odorata from seed.
This lovely plant has long disappeared from my mum’s garden, but returns every year in our borders, gently self-sowing to tiptoe softly around . I love its wiry dark red stems and buds, the elegant flowers that open a pale buttery colour and fade to apricot, and the sweet scent that gives rise to its name.
This year a new plant has sprung up in one of our borders which shows very different colouring: the flowers a rich clear lemon yellow, the stems and foliage a bright fresh green, with no hint of the red that suffuses my other plants. In fact, it looks strongly like the common evening primrose, Oenothera biennis. You can see the contrast in the later photographs.
I wonder fleetingly where this new arrival fits in the evening primrose family, I definitely prefer the softer tones and apricot/red colouring in my older plants. I suppose I should remove this one or at least its seedheads to avoid diluting future generations…
It’s a rather lovely visitor though.
hillwards 
I tried to establish this unsuccessfully in the garden. I think we are too shady for it.
Interesting. It certainly grows for us in our two sunniest beds, but my mum’s garden is South facing so it should have thrived there too. I wonder if it prefers our clay to her sandier soil…
At least you noticed there was a difference – sometimes I wonder what new species are created in our gardens but we miss them
Yes that probably happens more often than we realise.
The new evening primrose has a very different habit as well as colouring, with a big cluster of buds at the tip while on our version flowers branch singly and in a much more airy fashion.