The world's tallest tree is found in northern California - it's a redwood that stands 379 feet tall. This tree and its relatives are the largest single organisms in the world, but just how big can these trees really get?
To put into some perspective the size of Giant Sequoias and Coast Redwoods - the two tree species most capable of creating super-sized members - these trees are on average about three times as long as a blue whale, and sixteen times the mass. And there's plenty of incentive for trees to grow as tall as they can, as it allows them to get more sunlight, and thus more energy, than their shorter counterparts.
Trees might go on growing forever if it wasn't for gravity. The higher up trees grow, the more energy is needed to transport water from the root system to its leaves or needles up top. That means the leaves or needles will get smaller and smaller, until the amount of energy they can gain from photosynthesis is outweighed by the energy expended in order to haul up water in the first place. At that point, there's no point for the tree to keep growing, and it stops.
So what, precisely, is the upper limit for the world's biggest trees? According to biologists at Northern Arizona University, this cutoff point is somewhere between 400 and 426 feet - perhaps nearly fifty feet taller than any tree currently in existence, although it's thought that even taller trees have died or been cut down in the past.
So why do redwoods grow so tall? Northern California has the perfect mix of good soil, nice climate, and plenty of rain for the trees to grow tall. These excellent conditions mean that tons of trees can thrive, which in turn means they need to grow as high as they can to get access to sunlight. It's basically like there's too much of a good thing, which is what causes these trees to grow to such tremendous sizes.
So then, if we want to see trees reach their absolute maximum height, we may need to cram in even more sequoias and redwoods into northern California, forcing them to grow still higher to get sunlight. Of course, if we want to see a 400-foot tree in our lifetime, we really will have needed to plant all these new trees back in the 1600s. So, if you'll excuse me, I need to go invent a time machine...for purely arboreal purposes, you understand.