It is P.elatior of Jacq., which certainly looks, when growing, to common eyes different from the common oxlip.

I will fight you to the death that as primrose and cowslip are different in appearance (not to mention odour, habitat and range), and as I can now show that, when they cross, the intermediate offspring are sterile like ordinary hybrids, they must be called as good species as a man and a gorilla.
I agree that if Scott's red cowslip grew wild or spread itself and did not vary [into] common cowslip (and we have absolutely no proof of primrose or cowslip varying into each other), and as it will not cross with the cowslip, it would be a perfectly good species.

The power of remaining for a good long period constant I look at as the essence of a species, combined with an appreciable amount of difference; and no one can say there is not this amount of difference between primrose and oxlip.
(PLATE: HUGH FALCONER, 1844.

From a photograph by Hill & Adamson.) LETTER 180.

HUGH FALCONER TO W.SHARPEY.
(180/1.