India is at a geographical crossroads, with a long history of visitors and plant introductions. International trees are those that remind us of the other nations and countries of Earth, and are usually exotic species that were only brought to India in relatively recent times.
Eucalyptus trees, for example, are ambassadors from the southern continent of Australia, and the European oak trees are representatives from the British Isles. The Chinnar trees of Kashmir were brought from Turkey, and the Cryptomeria, from Japan.
Most of these trees were brought over to India for their utilitarian purposes, for timber, food, or shade. The British, especially, experimented in large-scale plant introductions. Some of the trees they bought, such as the vilaiti keekar, became feral and formed new, invasive forests on the landscape of India.
These trees can help one to imagine the terrain, and the vegetation, of distant lands filled with foreign people. By understanding the trees which they live with, perhaps we can learn a bit about the nations of the world.