Some seeds are light enough by themselves. Using the wind is a useful way of spreading seeds. Many seeds are dispersed by wind, and. a number of them are specially designed fruits. The fruits of dandelions, thistles and many other members of the daisy, family are crowned with hairy plumes that act as parachutes. The seeds of willowherbs and willows also have plumes like this. The fruits of old man's beard have hairy 'tails' that help the wind to carry them through the air. On trees the most spectacular winged fruits are found. With the seed in between a birch fruit has a pair of small wings. With the seed at one end an ash fruit forms a long, aerodynamic wing. As they fall to the ground Maple trees have two-seeded, double-winged fruits that spin like helicopter blades.