Sex and the hazel.
The Hazels are in flower, spring must be here. Hazel trees are monoecious, with both male and female flowers on the same tree. However, hazel flowers can only be pollinated by pollen from other hazel trees. The yellow male catkins appear before the leaves and hang in clusters, from around February. The female flowers are tiny and bud-like with red styles. Once pollinated by the wind, the female flowers develop into the familiar hazel-nut with a woody shell surrounded by a cup of leafy bracts.