It's hard to overstate the importance of trees. Their appearance more than 300 million years ago was a turning point for Earth, helping transform its surface into a bustling utopia for land animals. Puzzle over six amazing photos showcasing the majesty of trees.

image by Arnaud Mesureur

Trees are the longest living organisms on Earth, and never die of old age. A 2017 census found 60,065 different species, although nearly 58 percent are single-country endemics, meaning each one naturally occurs only within the borders of a single nation.

One large tree can provide a day’s supply of oxygen for up to four people and more than 20% of the world’s oxygen is produced in the Amazon Rainforest. Trees also absorb carbon dioxide (CO2), removing and storing the carbon while releasing the oxygen back into the air. In one year, an acre of mature trees absorbs the amount of CO2 produced by a car driven 26,000 miles. Trees provide other benefits as well, such as lowering surface and air temperatures by providing shade and the evaporation of water from trees has a cooling influence too.

Arbor Day is a holiday in which individuals and groups are encouraged to plant trees. The Arbor Day Foundation provides free information about planting and caring for trees.