Walking above Starney Bay today the primroses (Primula vulgaris) were looking lovely on the grassy slopes.

If you take a closer look at the primroses you see you will notice that there are two different types of flower, Pin and Thrum:

Thrum flower on the left, Pin flower on the right

This is a clever adaptation that some plants have to make sure there is more cross pollination and therefore genetic diversity.  The thrum flowers have the male parts of the plant, the anthers, at the top of the flower tube, with the female part, the stigma is half way down.  The pin flowers have the stigma at the top, and the anthers half way down.  Primroses are a good early nectar source for insects, and the idea is that when they stick their feeding apparatus, or proboscis, down into the flower the pollen from the anthers will get stuck at a certain place on the proboscis.  For example after visiting a thrum flower, the pollen would get stuck at the top of the proboscis, since the anthers are at the top of the flower tube.  If the insect then visited a pin flower, with the receptive stigma at the top, the pollen would be in the perfect place to rub off and fertilize the plant! 


Next time you pass a clump of primroses, why not see if you can spot the two different types of flower?  Lizy