Plants have evolved all sorts of strategies for distributing their seeds over a wide
area. Some like Hawthorn and Elder, wrap the seed in a tempting fleshy cover in
the hope that it will be eaten by a bird or animal; the seed passes through the digestive
system intact, hopefully arriving in pastures new. Other plants like Broom and Himalayan
Balsam have seed pods whose two halves try to contract against each other as they
dry in the sun, eventually the pod splits allowing the pods to twist and coil up
in a fraction of a second, catapulting the seeds over a wide area.
However, one of the most effective strategies for dispersing seeds far and wide is
to use the wind. A small seed on its own would need a strong gust of wind to move
it away from the parent plant, but add a small parachute and the slightest breeze
will whisk it aloft. Once airborne and depending on the weather conditions, the seed
can travel huge distances. As can be seen from the images there are numerous variations
on a theme; some like Willowherb use a tangled mass of fine hairs to surround the
seed, while the Daisy family have distinctly tidier arrangements and look like miniature
umbrellas. The small hooks and barbs on the individual hairs may help to anchor the
seed once it lands.