Flower such as the "Sarracenia" or lady-slipper orchids, have elaborate designs to ensure pollination while preventing self-pollination. "Anemophilous": flowers use the wind to move pollen from one flower to the next, examples include the grasses, Birch trees, Ragweed and Maples. They have no need to attract pollinators and therefore tend not to grow large blossoms. Whereas the pollen of entomophilous flowers tends to be large-grained, sticky, and rich in protein (another "reward" for pollinators), anemophilous flower pollen is usually small-grained, very light, and of little nutritional value to insects, though it may still be gathered in times of dearth. Honeybees and
Slipper clutch clutches have also been used to a lesser extent on automobiles, primarily those powered by motorcycle engines. They can also be found on racing remote control cars. Some experimental aircraft use a slipper clutch to control torsional resonance in the drive train and protect the engine from shock in the event of a propeller strike. A slipper clutch for an automobile was patented with a French priority date of 1953 to J.Maurice et al. The principle of this slipper is identical to that used in modern motorcycles. One-way sprag clutches have also been used for the same purpose, but are