lucas asks:How tall can trees grow?

The records on tree height aren't great and until recently it's been hard trying to measure tree height, most recently they've started using laser to measure the height and the current record is set at 115m which is in itself just astonishing

Actually according to a study by scientists, no tree species at present times can grow more than 130 metres or 427 feets.The world's tallest trees are California redwoods, technically known as Sequoia sempervirens.
It is also interesting to know that the leaf size strts getting smaller and smaller as you go up because water can't reach at such a height so well.

Most trees become broad and not tall...

Yes, the Sequoias are the tallest trees on the planet, without question. They have achieved their maximum growth potential as Mother Nature deems it so. Other plant life is equally beautiful in its own way.

Is that only in the U.S.A? Because maybe there's taller trees somewhere else?