Final answer:
Mangrove trees are characteristic of tropical coastal wetlands due to their specialized aerial roots and adaptability to oxygen-poor sediments.
Step-by-step explanation:
The characteristic tree of tropical coastal wetlands is the mangrove. Mangroves have specific adaptations such as aeriel roots, known as pneumatophores, that assist with gas exchange and provide stability in the soft, oxygen-poor sediments of coastal waters. These adaptations make mangroves well-suited to the challenging conditions of tropical coastal wetlands.