|Thrum-eyed Primula. 6 February, 2014|
In the thrum-eyed form the female organs cannot be seen as they are situated half way down the corolla tube.
|Pin-eyed Primula. 6 February, 2014|
In the pin-eyed form the situation is reversed: the female stigma, looking like a drumstick, clearly protrudes from the mouth of the corolla tube; the male organs cannot be seen.
Ideally a visiting insect will go to a thrum-eyed flower first and receive a dusting of pollen from the male organs. It will go on to a female flower and deposit pollen on the sticky stigma and pollination is achieved.
The object of the exercise is, of course, to try and ensure cross-pollination. Although our wild Primrose, Primula vulgaris, is far less common than a century ago it is still abundant in places, testimony to the success of this arrangement. All our other native primulas - Bird's Eye Primrose (Primula farinosa), Oxlip (Primula elatior) and Cowslip, (Primula veris) have similar arrangements.