Seeds on the fly.

George Yatskievych will never forget the in his office. The fruit happened to be hanging on a cannonball tree. When it blew, 'its shattered a pane go glass and gouged a section of metal filing cabinet," the botanist recalls. "Fortunately, it happened at night, when no one was there."

Maybe Yatskievych should have left the cannonball in its native tropical habitat. There, the explosion serves an important purpose: It is the mechanism the tree uses to disperse its seeds--send them sailing away to start a new life.

LEAVING HOME

Casting out your children this way--as far as 14 meters in the case of the cannonball--and at such a young age, may seem cruel and unusual to you. After all, we humans would never survive such treatment; as babies, we depend completely om our patients for food and protection.

But plants are different. By dispersing its seeds, a parent plant actually helps its offspring get a good start in life. That, in turn, increased the odds that the parent plant will fulfill its main objective in life, one that it shares with all living things: to pass on its genes to subsequent generations.

Just think of what would happen of the seeds stuck around. "A small plant growing underneath a parent plant is going to have a much lower chance of survival," explains botanist Wayt Thomas. "It's going to be in direct competition with a plant that's already much larger than itself." Imagine trying to find enough sunlight, moisture, and nutrients--the things plants need to live--under those conditions.

Plants with adaptations such as exploding fruits avoid that parent-offspring competition, says Thomas. And if the seeds fly far and wide, he adds, the offspring won't even have to compete with one another.

It wouldn't make sense for a plant to have all its seeds land in one place anyway. What if that place turned out to be one where the plant couldn't grow? A strategy of wide dispersal increases the chance that at least some seeds will find a habitat where they can grow.

MORE THAN ONE WAY ...

Lots of plants use the exploding dispersal technique, from ferns to witch hazel to trees like the cannonball. You might even hear a few ballistic plants snap, crackle, and pop as you walk through the woods this fall.

But explosion is just one of whole array of seed dispersal mechanisms. Different plants have developed different strategies to give their ofspring a "flying" start.

You can check out some of these methods in the pictures on these pages. Then try the activities on the next page to uncover some seed secrets yourself.