By Letty de Weger (Leiden University Medical Centrum)
In the coming weeks lots of pollen can be collected. Due to the nice, sunny weather birch trees are in full flower and release their pollen into the air. This is of course not so good news for the individuals sensitized to the pollen of birch because they can suffer from hay fever symptoms.
Next to birch also the ash trees are flowering. The black buds of the ash branches have bursted, releasing the purple anthers (first figure). Among those anthers you can see some that release their yellow pollen (second figure).
For more about our project on pollen and pollution in the Netherlands see other posts: