Silver birch seeds

 Silver birch seed catkins are ripening now and fall apart at the slightest touch. Their seeds are an important food resource for several small finches, including siskins, goldfinches and redpolls.

When the catkins disintegrate they separate into woody, arrow-shaped bracts, releasing the much smaller seeds that are surrounded by a broad translucent wing. They can be carried long distances on a windy day - one of the factors that make this tree such a prolific coloniser of open habitats.