Hazel pollen. Light micrograph of pollen grains from the Hazel tree Corylus avellana. These microspores are shed from male catkins (hanging pollen- bearing structures) on the Hazel tree, released into the air and carried by wind to pollinate the female flowers. Large quantities of Hazel pollen occur as a fine yellow mist at springtime in parts of Europe, and may contribute to attacks of hay fever (allergic rhinitis). Magnification: x125 at 35mm size.