This green dragon was a female dragon that lived around the beginning of the Hundred Year War. She is known to have eventually laid one egg.
This dragon made her nest in a high mountain located in the Fire Nation and laid an egg.
Some time later, a group of poachers obtained a map leading to the green dragon's nest. The green dragon was lured out by one of the poachers, while the others attempted to grab her egg. However, another map had been obtained by Aang and Kuzon, and stumbling upon the poachers, they tricked them into thinking the dragon had returned. The poachers ran off, but the green dragon's egg was nearly smashed when she returned and knocked it out of Aang's hands, incorrectly assuming they wanted to steal her egg.
Aang managed to catch the egg just before it hit the ground, convincing the mother dragon that they were no threat to her or her offspring. She was grateful, but refused to take them for a ride as Kuzon had hoped.
There were six known dragons with her introduction: Sozin's dragon, Fang, Ran and Shaw, herself, and her child, though when Aang and Kuzon encountered the dragon, her child had not yet hatched from its egg.
Unlike other dragons, this one has two sets of wings: the main flying pair and a secondary, smaller pair just below them.
Kuzon called the green dragon a "big chicken lizard".