Which Is the Thickest and Which Is the Tallest Tree?

On the earth various kinds of trees grow, of them the thickest is the "World Grandpa" that grows in North America. It is so thick that a horse- drawn carriage can freely pass through a tunnel made in its trunk. Though it is the thickest, it is not the tallest. The tallest one is the eucalyptus growing in Oceania; its height is on average about 100 metres and the tallest can be 150 metres, which is higher than the total height of 100 children.