NATURE|VOL 435 | 12 MAY 2005 |
The release of stored elastic energy often drives rapid movements in animal systems 1 and plant components employing this mechanism should be able to move with similar speed. Here we describe how the flower stamens of the bunchberry dogwood (Cornus canadensis) rely on this principle to catapult pollen into the air as the flower opens explosively3–5. Our high-speed video observations show that the flower opens in less than 0.5 ms — to our knowledge, the fastest movement so far recorded in a plant. Indoors, pollen is transported over 22 cm (more than 100 times the size of the flower) and outdoors, in the presence of a steady wind, pollen can move farther than a meter. Exploding flowers enhance insect pollination and may allow wind pollination, adding to growing evidence that flowers often use multiple pollination mechanisms
Bunchberry stamens are designed like miniature medieval trebuchets — specialized catapults that maximize throwing distance by having the payload (pollen in the anther) attached to the throwing arm (filament) by a hinge or flexible strap (thin vascular strand connecting the anther to the filament tip). This floral trebuchet enables stamens to propel pollen upwards faster than would a simple catapult. After the petals open, the bent filaments unfold, releasing elastic energy.The tip of the filament follows an arc,but the rotation of the anther about the filament tip allows it to accelerate pollen upwards to its maximum vertical speed, and the pollen is released only as it starts to accelerate horizontally.
To catapult its pollen, bunchberry flower petals open, each petal is separated and flipped backwards, almost instantaneously (in less than half a millisecond) the stamen unfurls, catapulting pollen into the air, sending it off to pollinate other bunchberries. 2 This causes the pollen to be subjected to 2,400 times the force of gravity!
Building this plant trebuchet took careful planning and complex design, testifying to the creative designer, God who created all things. Did you know that this Designer is Jesus Christ?
Can you imagine a plant that moves so fast that science didn't know what it was doing until recently? The plant is a forest wildflower found in North America and called the Bunchberry dogwood.
A few botanists had noted a strange "poof" associated with the plant, but no one knew what was going on. Researchers at Williams College in Williamstown, Massachusetts, were studying the plant when they experienced the "poof." Wanting to track down what the plant was doing, they got a high-speed video camera that can shoot 1,000 frames per second. Amazingly, that camera was too slow to clearly catch what the plant was doing. So they got a higher-speed camera that could shoot 10,000 frames per second.
When they reviewed the video, they discovered that the flower was releasing pollen at an amazing speed. They calculated that the gravitational force on the pollen as it is released is 800 times the force astronauts endure when they blast into space. This wonder is accomplished by the flowers' very elastic petals which are part of a design that looks like a trebuchet – a medieval catapult.